View allAll Photos Tagged pseudanthium
Bellis perennis is a common European species of daisy, often considered the archetypal species of that name. Many related plants also share the name daisy, so to distinguish this species from other daisies it is sometimes qualified as common daisy, lawn daisy or English daisy. Historically, it has also been commonly known as bruisewort and occasionally woundwort. Bellis perennis is native to western, central and northern Europe, but widely naturalised in most temperate regions including the Americas and Australasia. It is a perennial herbaceous plant with short creeping rhizomes and rosettes of small rounded or spoon-shaped leaves that are from 2–5 cm long and grow flat to the ground. The flowerheads are composite, in the form of a pseudanthium, consisting of many sessile flowers about 2–3 cm in diameter, with white ray florets (often tipped red) and yellow disc florets. 5952
Die Sonnenblume ist eine bis zu 2 Meter tief wurzelnde einjährige kultivierte Pflanze. Sie ist sehr photosyntheseaktiv; eine große Pflanze bindet pro Tag das in einem Raum von 100 Kubikmetern vorhandene Kohlendioxid. Allerdings sind die Pflanzen sehr lichtabhängig d. h., die Netto-Photosyntheserate steht in direktem Verhältnis zum Logarithmus der Lichtintensität, deshalb bleiben bereits geringfügig schlechter besonnte Pflanzen wesentlich kleiner. Sie ist eine typische Pflanze warmer Standorte, d. h., sie ist ein Wärmekeimer, sie hat ihr maximales Wachstum bei 20 Grad Celsius und ihre Keimblätter legen sich nachts zusammen.
Blütenökologisch sind die Scheinblüten (Pseudanthium) große „Körbchenblumen“, die oft aus über 15.000 Einzelblüten bestehen. Die Blüten sind vormännlich. Die zungenförmigen Randblüten sind steril und haben eine hohe UV-Reflexion. Die Scheibenblüten sind zwittrig. Die Bestäubung erfolgt durch verschiedene Insekten. Der Nektar hat zur Zeit der Hauptproduktion zwischen 10 und 14 Uhr auch den höchsten Zuckergehalt von 35 %. Die Blütenkörbe richten sich fast immer auf „Mittag“ ein; die Sonnenblumen sind also Kompasspflanzen.
Die Eigenart der Pflanze, sich immer dem Sonnenlicht zuzuwenden, nennt man Heliotropismus. An sonnigen Tagen verfolgt die Knospe die Sonne von Ost nach West, während sie sich nachts oder in der Morgendämmerung nach Osten zurückdreht. Es drehen sich jedoch nur die Blätter und Knospen der jungen Pflanze zur Sonne. Blüten und Fruchtstände tun dies nicht mehr. Diese weisen in der Regel nach Osten. Der Stamm verhärtet am Ende der Knospenstufe seine östliche Ausrichtung und, wenn die Überstrahlungsstufe erreicht wird, „friert“ der Stamm sie gewissermaßen ein. Blühende Sonnenblumen sind nicht mehr heliotrop, und die meisten Köpfe zeigen in Richtung des Sonnenaufgangs!
The name of the genus was given as a tribute to Italian botanist Giovanni Zantedeschi (1773–1846) .
Takes the form of a solitary pseudanthium (false flower), with a showy white or yellow spathe (a specialised petal like bract) shaped like a funnel with a yellow, central, finger-like spadix, which carries the true flowers.
Bellis perennis, the daisy, is a European species of the family Asteraceae, often considered the archetypal species of the name daisy. To distinguish this species from other plants known as daisies, it is sometimes qualified as common daisy, lawn daisy or English daisy.
Bellis perennis is a perennial herbaceous plant growing to 20 centimetres (8 inches) in height. It has short creeping rhizomes and rosettes of small rounded or spoon-shaped leaves that are from 2 to 5 cm (3⁄4–2 in) long and grow flat to the ground. The species habitually colonises lawns, and is difficult to eradicate by mowing, hence the term 'lawn daisy'. It blooms from March to September and exhibits the phenomenon of heliotropism, in which the flowers follow the position of the sun in the sky.
The flowerheads are composite, about 2 to 3 cm (3⁄4–1+1⁄4 in) in diameter, in the form of a pseudanthium, consisting of many sessile flowers with white ray florets (often tipped red) and yellow disc florets. Each inflorescence is borne on a single leafless stem 2 to 10 cm (3⁄4–4 in), rarely 15 cm (6 in) tall. The capitulum, or disc of florets, is surrounded by two rows of green bracts known as "phyllaries". The achenes are without pappus.
Every day I try to learn something new. Today I discovered that the center of a daisy flower is called a Pseudanthium. A Pseudanthium is a special type of plant in which anything from a small cluster to hundreds or sometimes thousands of flowers are grouped together to form a single flower-like structure. That made perfect sense when I noticed that there were very small flowers clustered together in the center. Perhaps we should all keep a magnifying glass in our pockets.
This sunflower self seeded in our garden this summer!
The common sunflower (Helianthus annuus) is a species of large annual forb of the daisy family Asteraceae. The common sunflower is harvested for its edible oily seeds, which are often eaten as a snack food. They are also used in the production of cooking oil, as food for livestock, as bird food, and as a plantings in domestic gardens for aesthetics. Wild plants are known for their multiple flower heads, whereas the domestic sunflower often possesses a single large flower head atop an unbranched stem.
The plant has an erect rough-hairy stem, reaching typical heights of 3 metres (10 feet). The tallest sunflower on record achieved 9.17 m (30 ft 1 in). Sunflower leaves are broad, coarsely toothed, rough and mostly alternate; those near the bottom are largest and commonly heart-shaped.
The plant flowers in summer. What is often called the "flower" of the sunflower is actually a "flower head" (pseudanthium), 7.5–12.5 centimetres (3–5 in) wide,[4] of numerous small individual five-petaled flowers ("florets"). The outer flowers, which resemble petals, are called ray flowers. Each "petal" consists of a ligule composed of fused petals of an asymmetrical ray flower. They are sexually sterile and may be yellow, red, orange, or other colors. The spirally arranged flowers in the center of the head are called disk flowers. These mature into fruit (sunflower "seeds").
The prairie sunflower (H. petiolaris) is similar in appearance to the wild common sunflower; the scales in its central disk are tipped by white hairs.
For further information please visit en.wikipedia.org/wiki/Common_sunflower
Knapweeds are robust weedy plants. Their leaves, spiny in some species, are usually deeply divided into elongated lobes at least in the plants' lower part, becoming entire towards the top. The "flowers" (actually pseudanthium inflorescences) are diverse in colour, ranging from intense blues, reds and yellows to any mixture of these and lighter shades towards white. Often, the disk flowers are much darker or lighter than the ray flowers, which also differ in morphology and are sterile. Each pseudanthium sits atop a cup- or basket-like cluster of scaly bracts, hence the name "basketflowers". Many species, in particular those inhabiting more arid regions, have a long and strong taproot.... Wikipedia
The flowers are born in an unusual way within the inflorescence: the greenish-yellow posterior petals are directed to the centre of the pseudo-umbel and the white anterior ones to the periphery, giving the appearance of a daisy. This arrangement of the flowers, called a pseudanthium (all the flowers in the pseudo-umbel together give the appearance of a single flower), probably plays a role in the pollination biology of the species.
The sunflower (Helianthus annuus) is an annual plant in the family Asteraceae, with a large flower head (capitulum). The stem of the flower can grow up to 3 metres tall, with a flower head that can be 30 cm wide. Other types of sunflowers include the California Royal Sunflower, which has a burgundy (red + purple) flower head.
The flower head is actually an inflorescence made of hundreds or thousands of tiny flowers called florets. The central florets look like the centre of a normal flower, and the outer florets look like yellow petals. All together they make up a "false flower" or pseudanthium. The benefit to the plant is that it is very easily seen by the insects and birds which pollinate it, and it produces thousands of seeds.
The sunflower is the state flower of Kansas. That is why Kansas is sometimes called the Sunflower State. To grow well, sunflowers need full sun.
"What is often called the "flower" of the sunflower is actually a "flower head" (pseudanthium), 7.5–12.5 centimetres (3–5 in) wide, of numerous small individual five-petaled flowers ("florets"). The outer flowers, which resemble petals, are called ray flowers. Each "petal" consists of a ligule composed of fused petals of an asymmetrical ray flower. They are sexually sterile and may be yellow, red, orange, or other colors. The spirally arranged flowers in the center of the head are called disk flowers. These mature into fruit (sunflower "seeds")."
Zantedeschia (/ˌzæntɪˈdɛskiə/) is a genus of eight species of perennial flowering plants, native to southern Africa. Takes the form of a solitary pseudanthium (false flower), with a showy white, yellow, rose, purple spathe (a specialised petal like bract) shaped like a funnel with a yellow, central, finger-like spadix, which carries the true small flowers.
The sunflower is an annual cultivated plant that roots up to 2 metres deep. It is very active in photosynthesis; a large plant binds the carbon dioxide present in a space of 100 cubic metres per day. However, the plants are very light-dependent, i.e. the net photosynthesis rate is in direct proportion to the logarithm of the light intensity, which is why even slightly less sunlit plants remain considerably smaller. It is a typical plant of warm locations, i.e. it is a heat germinator, it has its maximum growth at 20 degrees Celsius and its cotyledons fold at night.
In terms of flower ecology, the pseudanthium flowers are large "basket flowers", often consisting of over 15,000 individual flowers. The flowers are pre-male. The tongue-shaped marginal flowers are sterile and have a high UV reflection. The disc flowers are hermaphrodite. Pollination is carried out by various insects. The nectar also has the highest sugar content of 35 % at the time of peak production between 10 am and 2 pm. The flower heads are almost always orientated to "midday"; sunflowers are therefore compass plants.
Die Sonnenblume ist eine bis zu 2 Meter tief wurzelnde einjährige kultivierte Pflanze. Sie ist sehr photosyntheseaktiv; eine große Pflanze bindet pro Tag das in einem Raum von 100 Kubikmetern vorhandene Kohlendioxid. Allerdings sind die Pflanzen sehr lichtabhängig d. h., die Netto-Photosyntheserate steht in direktem Verhältnis zum Logarithmus der Lichtintensität, deshalb bleiben bereits geringfügig schlechter besonnte Pflanzen wesentlich kleiner. Sie ist eine typische Pflanze warmer Standorte, d. h., sie ist ein Wärmekeimer, sie hat ihr maximales Wachstum bei 20 Grad Celsius und ihre Keimblätter legen sich nachts zusammen.
Blütenökologisch sind die Scheinblüten (Pseudanthium) große „Körbchenblumen“, die oft aus über 15.000 Einzelblüten bestehen. Die Blüten sind vormännlich. Die zungenförmigen Randblüten sind steril und haben eine hohe UV-Reflexion. Die Scheibenblüten sind zwittrig. Die Bestäubung erfolgt durch verschiedene Insekten. Der Nektar hat zur Zeit der Hauptproduktion zwischen 10 und 14 Uhr auch den höchsten Zuckergehalt von 35 %. Die Blütenkörbe richten sich fast immer auf „Mittag“ ein; die Sonnenblumen sind also Kompasspflanzen.
Was für einen Laien wie eine einzige Blüte aussieht, ist tatsächlich eine Scheinblüte (Pseudanthium). Das Blütenkörbchen richtet sich aufgrund des Heliotropismus immer nach der Sonne und schließt sich abends sowie bei schlechtem Wetter.
Typisch für Gänseblümchen ist die Verbreitung der Achänen durch den Regen. Dadurch werden die Achänen im Umkreis der Mutterpflanze von ihr weggeschleudert.
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For the past three days, I introduced you to the amazing Leucodendrons. Now two more species that have the same characteristic, the Euphorbia.
The Euphorbia also have a unique kind of pseudanthium, called a cyathium, where each flower in the head is reduced to its barest essential part needed for sexual reproduction. The individual flowers are either male or female, with the male flowers reduced to only the stamen, and the females to the pistil. **These flowers have no sepals, petals, or other parts that are typical of flowers in other kinds of plants.**
Euphorbia is a very large and diverse genus of flowering plants, commonly called spurge, in the spurge family.Euphorbias from the deserts of Southern Africa and Madagascar have evolved physical characteristics and forms similar to cacti of North and South America, so they (along with various other kinds of plants) are often incorrectly referred to as cacti.
I first found this Mysinites at Bancroft Garden last year, and I had a devil of a time identifying it because I used the petals at the criteria. But those flowers are the leaves. Euphorbia myrsinites, the myrtle spurge, blue spurge, or broad-leaved glaucous-spurge, is a succulent species of flowering plant in the spurge family Euphorbiaceae. The plant is native to southeastern Europe and Asia Minor, from Italy east through the Balkans to Crimea and Turkey.
Only one small purple floret remains at the base of the capitulum of this purple coneflower.
Decatur (Winnona Park), Georgia, USA.
14 June 2021.
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▶ Purple coneflower = Echinacea purpurea, native to eastern and midwestern North America.
▶ Capitulum spike = a Bond villain?
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▶ Photo by Yours For Good Fermentables.com.
▶ For a larger image, type 'L' (without the quotation marks).
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▶ Camera: Olympus OM-D E-M10 II.
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— Edit: Photoshop Elements 15, Nik Collection.
▶ Commercial use requires explicit permission, as per Creative Commons.
The sunflower (Helianthus annuus) is an annual plant in the family Asteraceae, with a large flower head (capitulum). The stem of the flower can grow up to 3 metres tall, with a flower head that can be 30 cm wide. Other types of sunflowers include the California Royal Sunflower, which has a burgundy (red + purple) flower head.
The flower head is actually an inflorescence made of hundreds or thousands of tiny flowers called florets. The central florets look like the centre of a normal flower, and the outer florets look like yellow petals. All together they make up a "false flower" or pseudanthium. The benefit to the plant is that it is very easily seen by the insects and birds which pollinate it, and it produces thousands of seeds.
The sunflower is the state flower of Kansas. That is why Kansas is sometimes called the Sunflower State. To grow well, sunflowers need full sun. 953
One of the last species I found was this Pacific Forktail. Not much to say about it: Ischnura cervula, the Pacific forktail, is a species of narrow-winged damselfly in the family Coenagrionidae. It is found in Central America and North America.
Now, of much greater importance and interest is the Duck Weed. Lemnoideae is a subfamily of flowering aquatic plants, known as duckweeds, water lentils, or water lenses. They float on or just beneath the surface of still or slow-moving bodies of fresh water and wetlands. Also known as bayroot, they arose from within the arum or aroid family (Araceae) - flic.kr/p/2m51zRE.
These plants have a simple structure, lacking an obvious stem or leaves. The greater part of each plant is a small organized "thallus" or "frond" structure only a few cells thick, often with air pockets (aerenchyma) that allow it to float on or just under the water surface. Depending on the species, each plant may have no root or may have one or more simple rootlets.[2]
Reproduction is mostly by asexual budding (vegetative reproduction), which occurs from a meristem enclosed at the base of the frond. Occasionally, three tiny "flowers" consisting of two stamens and a pistil are produced, by which sexual reproduction occurs. Some view this "flower" as a pseudanthium, or reduced inflorescence, with three flowers that are distinctly either female or male and which are derived from the spadix in the Araceae.
The flower of the duckweed genus Wolffia is the smallest known, measuring merely 0.3 mm long. The fruit produced through this occasional reproduction is a utricle, and a seed is produced in a bag containing air that facilitates flotation.
One of the more important factors influencing the distribution of wetland plants, and aquatic plants in particular, is nutrient availability. Duckweeds tend to be associated with fertile, even eutrophic conditions. They can be spread by waterfowl and small mammals, transported inadvertently on their feet and bodies,[5] as well as by moving water. In water bodies with constant currents or overflow, the plants are carried down the water channels and do not proliferate greatly. In some locations, a cyclical pattern driven by weather patterns exists in which the plants proliferate greatly during low water-flow periods, then are carried away as rainy periods ensue.
Duckweed is an important high-protein food source for waterfowl. The tiny plants provide cover for fry of many aquatic species. The plants are used as shelter by pond-water species such as bullfrogs and fish such as bluegills. They also provide shade and, although frequently confused with them, can reduce certain light-generated growths of photoautotrophic algae.
For at least six years, my primary source for dragon- and damselfly photography were three places in Heather Farm, a wonderful wildlife area given to the city a century ago for the enjoyment of "all citizens." In just three years - even before Covid - it seems that our City has deemed the wildlife part of the farm as unimportant. When I visited last week after a 15 month absence, duck weed had died, water flow was nonexistent, and in three areas, reeds had taken over a most beautiful lagoon where I photographed odonata but, even more, all manner of herons, ducks, and egrets! All gone! And I mean all! Seven Canada geese and, four mallards. Can you imagine a pond that once provided me with large populations of Ringed-necked ducks (flic.kr/p/2kNy5VY), Snowy egrets, *breeding* Double-crested cormorant colony, and a field of wild mustard that was the courtship, mating and nesting grounds for Redwinged blackbirds and a hunting ground for mated Red-shouldered hawks. All gone! And for what? An ill-conceived "community garden" that few were interested in, and now is a field of boxed weeds, fences that keep wildlife out, and cost more than enough to have maintained the two ponds (one a small lake), a stream, the lagoon, the mini-waterfall that was a breeding ground for the dragonflies, and six islands on which plants that were not native were planted and which died in less than 18 months and cost something like $7k each. They are still there. I saw one duck and dead plants. In four years, we've lost a treasure, a place where wild river otters and muskrat would nest during the summer (flic.kr/p/HagXWg). The two established nests are either in disrepair or have been torn down by the city. But basically, it's almost like planned neglect. I have a thousand images taken at Heather Farm from 2008 to 2019. There's nothing left to enjoy in the wild state. No hawks (flic.kr/p/2eqZiAj) breed there anymore, and they are neither fish nor vegetation to sustain such a wonderful population of wildlife ... even wildflowers. (The rose garden is kept up because it's a revenue source: wedding take place there, but I wonder how long that will occur since the devastation is just outside the rose garden gates.)
The sunflower (Helianthus annuus) is an annual plant in the family Asteraceae, with a large flower head (capitulum). The stem of the flower can grow up to 3 metres tall, with a flower head that can be 30 cm wide. Other types of sunflowers include the California Royal Sunflower, which has a burgundy (red + purple) flower head.
The flower head is actually an inflorescence made of hundreds or thousands of tiny flowers called florets. The central florets look like the centre of a normal flower, and the outer florets look like yellow petals. All together they make up a "false flower" or pseudanthium. The benefit to the plant is that it is very easily seen by the insects and birds which pollinate it, and it produces thousands of seeds.
The sunflower is the state flower of Kansas. That is why Kansas is sometimes called the Sunflower State. To grow well, sunflowers need full sun.
The sunflower (Helianthus annuus) is an annual plant in the family Asteraceae, with a large flower head (capitulum). The stem of the flower can grow up to 3 metres tall, with a flower head that can be 30 cm wide. Other types of sunflowers include the California Royal Sunflower, which has a burgundy (red + purple) flower head.
The flower head is actually an inflorescence made of hundreds or thousands of tiny flowers called florets. The central florets look like the centre of a normal flower, and the outer florets look like yellow petals. All together they make up a "false flower" or pseudanthium. The benefit to the plant is that it is very easily seen by the insects and birds which pollinate it, and it produces thousands of seeds.
The sunflower is the state flower of Kansas. That is why Kansas is sometimes called the Sunflower State. To grow well, sunflowers need full sun.
Die scheinbare Blüte ist ein Blütenstand, nur eine Scheinblüte (Pseudanthium). Die Schaufunktion entsteht durch die dicht weißfilzigen Hochblätter. Die eigentlichen Blüten sitzen zu vielen Hunderten, in einzelne Blütenkörbe organisiert, inmitten des Sterns beisammen und bilden zusammen mit den Hochblättern eine bestäubungsbiologische Einheit (Superpseudanthium).
Der blendend weiße Schimmer auf den Hochblättern entsteht dadurch, dass tausende kleine Luftbläschen an dem vielfach durcheinander gewirkten, krausen Haar das einfallende Licht reflektieren. Dies dient als Signal für nektarsuchende Insekten, als Verdunstungsschutz und als Schutz vor Wärmeverlust. Die Arbeitsgruppe um den belgischen Physiker Jean-Pol Vigneron der Universität Notre-Dame de la Paix in Namur hat herausgefunden, dass die Haare selbst aus parallelen Fasern mit 0,18 Mikrometern Durchmesser bestehen, was in der Größenordnung der Wellenlänge der UV-Strahlung liegt und zu deren Absorption führt. Das übrige Licht wird jedoch hindurchgelassen, sodass die Pflanze Photosynthese betreiben kann.
Bestäuber sind vor allem Fliegen sowie Hautflügler, Falter und Käfer. Die Scheinblüte bleibt bis in den Winter hinein erhalten.
Das Alpen-Edelweiß gilt in Österreich und Deutschland als stark gefährdet. Ursachen sind heute v. a. das Betreten und Befahren der verbliebenen Standorte, früher vor allem das teils gewerbsmäßige Pflücken. Auch in Österreich und der Schweiz steht das Alpen-Edelweiß in sämtlichen Bundesländern bzw. Kantonen unter strengem Naturschutz und darf nicht gepflückt werden. In Österreich wurde das Edelweiß bereits 1886 unter Naturschutz gestellt. Durch das Aufkommen des Tourismus in den Alpen war es rasch zu einem begehrten und haltbaren Souvenir geworden. Als ein Beispiel für gelungenen Schutz eines Vorkommens kann der Bestand an der Höfats in den Allgäuer Alpen aufgeführt werden. Dort wurden die vor allem in der Inflationszeit durch übermäßiges Pflücken stark zurückgehenden Restvorkommen des dort vorkommenden, bereits damals geschützten Alpen-Edelweiß durch die Allgäuer Bergwacht von 1935 bis 2007 zur Blütezeit bewacht. Hierzu hatte sie eigens ein Zelt und später eine Biwakschachtel errichtet. Heute haben sich dort die Bestände erholt und das Naturschutzbewusstsein der Berggänger ist größer geworden, sodass die Bewachung nicht mehr erforderlich ist. (Wikipedia)
200 shot focus stack at 35 mm. Not perfect since the air is rarely totally still in Aberdeenshire but promising.
Bellis perennis is a common European species of daisy of the family Asteraceae often considered the archetypal species of that name. Many related plants also share the name "daisy" so to distinguish this species from other daisies it is sometimes qualified as common daisy lawn daisy or English daisy. Historically it has also been commonly known as bruisewort and occasionally woundwort (although the common name woundwort is now more closely associated with Stachys). Bellis perennis is native to western central and northern Europe including remote islands such as the Faroe Islands but widely naturalised in most temperate regions including the Americas and Australasia. It is a perennial herbaceous plant with short creeping rhizomes and rosettes of small rounded or spoon-shaped leaves that are from 3/4 to 2 inches (approx. 2–5 cm) long and grow flat to the ground. The species habitually colonises lawns and is difficult to eradicate by mowing – hence the term 'lawn daisy'. Wherever it appears it is sometimes considered an invasive weed. It exhibits the phenomenon of heliotropism where the flowers follow the position of the sun in the sky. The flowerheads are composite in the form of a pseudanthium consisting of many sessile flowers about 3/4 to 1-1/4 in (approx. 2–3 cm) in diameter with white ray florets (often tipped red) and yellow disc florets. Each inflorescence is borne on single leafless stems 3/4 – 4 in (approx. 2–10 cm) rarely 6 in (approx. 15 cm) tall. The capitulum or disc of florets is surrounded by two rows of green bracts known as "phyllaries". The achenes are without pappus. en.wikipedia.org/wiki/Bellis_perennis
Bellis perennis is a common European species of daisy, often considered the archetypal species of that name. Many related plants also share the name daisy, so to distinguish this species from other daisies it is sometimes qualified as common daisy, lawn daisy or English daisy. Historically, it has also been commonly known as bruisewort and occasionally woundwort. Bellis perennis is native to western, central and northern Europe, but widely naturalised in most temperate regions including the Americas and Australasia. It is a perennial herbaceous plant with short creeping rhizomes and rosettes of small rounded or spoon-shaped leaves that are from 2–5 cm long and grow flat to the ground. The flowerheads are composite, in the form of a pseudanthium, consisting of many sessile flowers about 2–3 cm in diameter, with white ray florets (often tipped red) and yellow disc florets. 9045
The flower head is actually an inflorescence made of hundreds or thousands of tiny flowers called florets. The central florets look like the centre of a normal flower, and the outer florets look like yellow petals. All together they make up a "false flower" or pseudanthium
Sulfur cosmos, blooming in an ecotone between meadow and marshland.
Decatur (Legacy Park), Georgia, USA.
18 October 2023.
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▶ "Cosmos sulphureus is a species of annual flowering plant—known as sulfur cosmos and yellow cosmos— in the sunflower family, Asteraceae. It is native to Mexico, Central America, and northern South America, but naturalized in other parts of North and South America (and Korea and Japan).
The foliage of Cosmos sulphureus is opposite and pinnately divided [feather-like]. Its flowers —yellow, orange, or red— are produced in a capitulum [flower-head containing multiple blossoms] with a ring of broad ray florets and a center of disc florets, blooming spring through autumn. The plant height varies from 1 to 7 feet (30–210 cm). Although an annual, Cosmos sulphureus can re-seed itself.
In 1996, the Southeast Exotic Pest Plant Council declared cosmos sulphureus to be invasive in the southeastern U.S. "
— North Carolina Cooperative Extension.
— Wikipedia.
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▶ Photo by Yours For Good Fermentables.com.
▶ For a larger image, type 'L' (without the quotation marks).
— Follow on Facebook: YoursForGoodFermentables.
— Follow on Instagram: @tcizauskas.
— Follow on Vero: @cizauskas.
▶ Camera: Olympus OM-D E-M10 II.
— Lens: Olympus M.45mm F1.8.
— Edit: Photoshop Elements 15, Nik Collection (2016).
▶ Commercial use requires explicit permission, as per Creative Commons.
Bellis perennis is a common European species of daisy, often considered the archetypal species of that name. Many related plants also share the name daisy, so to distinguish this species from other daisies it is sometimes qualified as common daisy, lawn daisy or English daisy. Historically, it has also been commonly known as bruisewort and occasionally woundwort. Bellis perennis is native to western, central and northern Europe, but widely naturalised in most temperate regions including the Americas and Australasia. It is a perennial herbaceous plant with short creeping rhizomes and rosettes of small rounded or spoon-shaped leaves that are from approx. 2–5 cm long and grow flat to the ground. The flowerheads are composite, in the form of a pseudanthium, consisting of many sessile flowers about 2–3 cm in diameter, with white ray florets (often tipped red) and yellow disc florets. 12217
A pseudanthium (Greek for "false flower") or flower head is a special type of inflorescence, in which anything from a small cluster to hundreds or sometimes thousands of flowers are grouped together to form a single flower-like structure.~Wikipedia
F45
105mm
1/100 SS
1250 ISO
One shot minor processing in Photoshop
Die scheinbare Blüte ist ein Blütenstand, nur eine Scheinblüte (Pseudanthium). Die Schaufunktion entsteht durch die dicht weißfilzigen Hochblätter. Die eigentlichen Blüten sitzen zu vielen Hunderten, in einzelne Blütenkörbe organisiert, inmitten des Sterns beisammen und bilden zusammen mit den Hochblättern eine bestäubungsbiologische Einheit (Superpseudanthium).
Der blendend weiße Schimmer auf den Hochblättern entsteht dadurch, dass tausende kleine Luftbläschen an dem vielfach durcheinander gewirkten, krausen Haar das einfallende Licht reflektieren. Dies dient als Signal für nektarsuchende Insekten, als Verdunstungsschutz und als Schutz vor Wärmeverlust. Die Arbeitsgruppe um den belgischen Physiker Jean-Pol Vigneron der Universität Notre-Dame de la Paix in Namur hat herausgefunden, dass die Haare selbst aus parallelen Fasern mit 0,18 Mikrometern Durchmesser bestehen, was in der Größenordnung der Wellenlänge der UV-Strahlung liegt und zu deren Absorption führt. Das übrige Licht wird jedoch hindurchgelassen, sodass die Pflanze Photosynthese betreiben kann.
Bestäuber sind vor allem Fliegen sowie Hautflügler, Falter und Käfer. Die Scheinblüte bleibt bis in den Winter hinein erhalten.
Das Alpen-Edelweiß gilt in Österreich und Deutschland als stark gefährdet. Ursachen sind heute v. a. das Betreten und Befahren der verbliebenen Standorte, früher vor allem das teils gewerbsmäßige Pflücken. Auch in Österreich und der Schweiz steht das Alpen-Edelweiß in sämtlichen Bundesländern bzw. Kantonen unter strengem Naturschutz und darf nicht gepflückt werden. In Österreich wurde das Edelweiß bereits 1886 unter Naturschutz gestellt. Durch das Aufkommen des Tourismus in den Alpen war es rasch zu einem begehrten und haltbaren Souvenir geworden. Als ein Beispiel für gelungenen Schutz eines Vorkommens kann der Bestand an der Höfats in den Allgäuer Alpen aufgeführt werden. Dort wurden die vor allem in der Inflationszeit durch übermäßiges Pflücken stark zurückgehenden Restvorkommen des dort vorkommenden, bereits damals geschützten Alpen-Edelweiß durch die Allgäuer Bergwacht von 1935 bis 2007 zur Blütezeit bewacht. Hierzu hatte sie eigens ein Zelt und später eine Biwakschachtel errichtet. Heute haben sich dort die Bestände erholt und das Naturschutzbewusstsein der Berggänger ist größer geworden, sodass die Bewachung nicht mehr erforderlich ist. (Wikipedia)
simple.wikipedia.org/wiki/Sunflower
The sunflower (Helianthus annuus) is an annual plant in the family Asteraceae, with a large flower head (capitulum). The stem of the flower can grow up to 3 metres tall, with a flower head that can be 30 cm wide. Other types of sunflowers include the California Royal Sunflower, which has a burgundy (red + purple) flower head.
The flower head is actually an inflorescence made of hundreds or thousands of tiny flowers called florets. The central florets look like the centre of a normal flower, and the outer florets look like yellow petals. All together they make up a "false flower" or pseudanthium. The benefit to the plant is that it is very easily seen by the insects and birds which pollinate it, and it produces thousands of seeds.
The sunflower is the state flower of Kansas. That is why Kansas is sometimes called the Sunflower State. To grow well, sunflowers need full sun. They grow best in fertile, wet, well-drained soil with a lot of mulch. In commercial planting, seeds are planted 45 cm (1.5 ft) apart and 2.5 cm (1 in) deep.
Description
The outer petal-bearing florets are the sterile florets and can be yellow, red, orange, or other colours. The florets inside the circular head are called disc florets, which mature into seeds.
The flower petals within the sunflower's cluster are always in a spiral pattern. Generally, each floret is oriented toward the next by approximately the golden angle, 137.5°, producing a pattern of interconnecting spirals, where the number of left spirals and the number of right spirals are successive Fibonacci numbers. Typically, there are 34 spirals in one direction and 55 in the other; on a very large sunflower there could be 89 in one direction and 144 in the other.[1][2]
Sunflowers commonly grow to heights between 1.5 and 3.5 m (5–12 ft.). The tallest sunflower confirmed by Guinness World Records is 9.17 m (2014, Germany). In 16th century Europe the record was already 7.3 m (24 ft., Spain).[3] Most cultivars are variants of H. annuus, but four other species (all perennials) are also domesticated. This includes H. tuberosus, the Jerusalem Artichoke, which produces edible tubers.
As food
Sunflower "whole seed" (fruit) are sold as a snack food, after roasting in ovens, with or without salt added. Sunflowers can be processed into a peanut butter alternative, Sunbutter. In Germany, it is mixed together with rye flour to make Sonnenblumenkernbrot (literally: sunflower whole seed bread), which is quite popular in German-speaking Europe. It is also sold as food for birds and can be used directly in cooking and salads. Sunflower oil, extracted from the seeds, is used for cooking, as a carrier oil and to produce margarine and biodiesel, as it is cheaper than olive oil. A range of sunflower varieties exist with differing fatty acid compositions; some 'high oleic' types contain a higher level of healthy monounsaturated fats in their oil than Olive oil.
The cake remaining after the seeds have been processed for oil is used as a livestock feed. Some recently developed cultivars have drooping heads. These cultivars are less attractive to gardeners growing the flowers as ornamental plants, but appeal to farmers, because they reduce bird damage and losses from some plant diseases. Sunflowers also produce latex and are the subject of experiments to improve their suitability as an alternative crop for producing hypoallergenic rubber. Traditionally, several Native American groups planted sunflowers on the north edges of their gardens as a "fourth sister" to the better known three sisters combination of corn, beans, and squash.[9] Annual species are often planted for their allelopathic properties.[source?] However, for commercial farmers growing commodity crops, the sunflower, like any other unwanted plant, is often considered a weed. Especially in the midwestern USA, wild (perennial) species are often found in corn and soybean fields and can have a negative impact on yields. Sunflowers may also be used to extract toxic ingredients from soil, such as lead, arsenic and uranium. They were used to remove uranium, cesium-137, and strontium-90 from soil after the Chernobyl disaster (see phytoremediation).
Photos taken while complying with UK Coronavirus lockdown.
This was a single handheld shot taking advantage of the beautiful optics of the Tamron 35 mm lens when opened up to f1.8.
Bellis perennis is a common European species of daisy, of the family Asteraceae, often considered the archetypal species of that name. Many related plants also share the name "daisy", so to distinguish this species from other daisies it is sometimes qualified as common daisy, lawn daisy or English daisy. Historically, it has also been commonly known as bruisewort and occasionally woundwort (although the common name woundwort is now more closely associated with Stachys). Bellis perennis is native to western, central and northern Europe, including remote islands such as the Faroe Islands but widely naturalised in most temperate regions including the Americas and Australasia. It is a perennial herbaceous plant with short creeping rhizomes and rosettes of small rounded or spoon-shaped leaves that are from 3/4 to 2 inches (approx. 2–5 cm) long and grow flat to the ground. The species habitually colonises lawns, and is difficult to eradicate by mowing – hence the term 'lawn daisy'. Wherever it appears it is sometimes considered an invasive weed. It exhibits the phenomenon of heliotropism where the flowers follow the position of the sun in the sky. The flowerheads are composite, in the form of a pseudanthium, consisting of many sessile flowers about 3/4 to 1-1/4 in (approx. 2–3 cm) in diameter, with white ray florets (often tipped red) and yellow disc florets. Each inflorescence is borne on single leafless stems 3/4 – 4 in (approx. 2–10 cm), rarely 6 in (approx. 15 cm) tall. The capitulum, or disc of florets, is surrounded by two rows of green bracts known as "phyllaries". The achenes are without pappus. en.wikipedia.org/wiki/Bellis_perennis
The sunflower (Helianthus annuus) is an annual plant in the family Asteraceae, with a large flower head (capitulum). The stem of the flower can grow up to 3 metres tall, with a flower head that can be 30 cm wide. Other types of sunflowers include the California Royal Sunflower, which has a burgundy (red + purple) flower head.
The flower head is actually an inflorescence made of hundreds or thousands of tiny flowers called florets. The central florets look like the centre of a normal flower, and the outer florets look like yellow petals. All together they make up a "false flower" or pseudanthium. The benefit to the plant is that it is very easily seen by the insects and birds which pollinate it, and it produces thousands of seeds.
The sunflower is the state flower of Kansas. That is why Kansas is sometimes called the Sunflower State. To grow well, sunflowers need full sun.
It's already Spring in Camprodon
Bellis perennis L.
Captura: Camprodon, Ripollès, Girona, Catalunya.
CATALÀ:
Margaridoia perenne o margarideta perenne és una planta herbàcia molt comú als Països Catalans que creix de forma silvestre als prats o a les vores dels caminns. Popularment, són poc conegudes les seves propietats medicinals, però en realitat té moltes aplicacions. La margaridoia perenne (Bellis perennis) pertany a la família de les asteràcies o compostes. El primer binomi Bellis prové del terme llatí bellus que vol dir graciós, bonic fent referència a la flor. El segon binomi perenne és degut al fet que es pot trobar florida durant tot l'any, sobretot a la primavera.
Es coneix amb molts noms populars com margaridoia, margarideta (margalideta a les Balears) i pasqüeta (valencià), puix que és molt comuna a les nostres terres. Cal dir que aquesta planta, tot i que es coneix popularment com a margarida, el Gran diccionari de la llengua catalana dóna com a prototipus de margarida l'espècie Chrysanthemum frutescens que té el centre groc i les lígules blanques i esmenta que margarida és el nom d'altres espècies semblants.
VIQUIPÈDIA
ENGLISH:
Bellis perennis is a common European species of daisy, of the family Asteraceae, often considered the archetypal species of that name.
Many related plants also share the name "daisy", so to distinguish this species from other daisies it is sometimes qualified as common daisy, lawn daisy or English daisy. Historically, it has also been commonly known as bruisewort and occasionally woundwort (although the common name woundwort is now more closely associated with Stachys). Bellis perennis is native to western, central and northern Europe, including remote islands such as the Faroe Islands but widely naturalised in most temperate regions including the Americas and Australasia. t is a perennial herbaceous plant with short creeping rhizomes and rosettes of small rounded or spoon-shaped leaves that are from 3/4 to 2 inches (approx. 2–5 cm) long and grow flat to the ground. The species habitually colonises lawns, and is difficult to eradicate by mowing – hence the term 'lawn daisy'. It exhibits the phenomenon of heliotropism where the flowers follow the position of the sun in the sky.
The flowerheads are composite, in the form of a pseudanthium, consisting of many sessile flowers about 3/4 to 1-1/4 in (approx. 2–3 cm) in diameter, with white ray florets (often tipped red) and yellow disc florets. Each inflorescence is borne on single leafless stems 3/4 – 4 in (approx. 2–10 cm), rarely 6 in (approx. 15 cm) tall. The capitulum, or disc of florets, is surrounded by two rows of green bracts known as “phyllaries". The achenes are without pappus.
WIKIPEDIA
Socotran Fig Tree (Dorstenia gigas) is a succulent native to the Socotra Islands off the Horn of Africa.
#SocotranFigTree #Socotran #FigTree #Dorsteniagigas #Dorstenia #gigas #macro #photostack #inflorescence #flower #pseudanthium #hypanthium
Bellis perennis the daisy, is a European species of the family Asteraceae, often considered the archetypal species of the name daisy. To distinguish this species from other plants known as daisies, it is sometimes qualified as common daisy, lawn daisy or English daisy.
Bellis perennis is a perennial herbaceous plant growing to 20 centimetres (8 inches) in height. It has short creeping rhizomes and rosettes of small rounded or spoon-shaped leaves that are from 2 to 5 cm (3⁄4–2 in) long and grow flat to the ground. The species habitually colonises lawns, and is difficult to eradicate by mowing, hence the term 'lawn daisy'. It blooms from March to September and exhibits the phenomenon of heliotropism, in which the flowers follow the position of the sun in the sky.
The flowerheads are composite, about 2 to 3 cm (3⁄4–1+1⁄4 in) in diameter, in the form of a pseudanthium, consisting of many sessile flowers with white ray florets (often tipped red) and yellow disc florets. Each inflorescence is borne on a single leafless stem 2 to 10 cm (3⁄4–4 in), rarely 15 cm (6 in) tall. The capitulum, or disc of florets, is surrounded by two rows of green bracts known as "phyllaries". The achenes are without pappus.
Bellis may come from bellus, Latin for "pretty", and perennis is Latin for "everlasting".
The name "daisy", possibly originating with this plant, is considered a corruption of "day's eye", because the whole head closes at night and opens in the morning. Geoffrey Chaucer called it "eye of the day". In Medieval times, Bellis perennis or the English Daisy was commonly known as "Mary's Rose". It is also known as bone flower.
Historically, the plant has also been widely known as bruisewort, and occasionally woundwort (although this name is now more closely associated with the genus Stachys).
Bellis perennis is native to western, central and northern Europe, including remote islands such as the Faroe Islands, but has become widely naturalised in most temperate regions, including the Americas and Australasia. It prefers field-like habitats.
The species generally blooms from early to midsummer, although when grown under ideal conditions, it has a very long flowering season and will even produce a few flowers in the middle of mild winters.
It can generally be grown where minimum temperatures are above −35 °C (−30 °F), in full sun to partial shade conditions, and requires little or no maintenance. It has no known serious insect or disease problems and can generally be grown in most well-drained soils. The plant may be propagated either by seed after the last frost, or by division after flowering.
Though not native to the United States, the species is still considered a valuable ground cover in certain garden settings (e.g., as part of English or cottage inspired gardens, as well as spring meadows where low growth and some color is desired in parallel with minimal care and maintenance while helping to crowd out noxious weeds once established and naturalised).
Numerous single- and double-flowered varieties are in cultivation, producing flat or spherical blooms in a range of sizes (1 to 6 cm or 3⁄8 to 2+3⁄8 in) and colours (red, pink and white). They are generally grown from seed as biennial bedding plants. They can also be purchased as plugs in Spring.
It has been reported to be mostly self-fertilizing, but some plants may be self-sterile.
Bellis perennis may be used as a potherb. Young leaves can be eaten raw in salads, or cooked, though the leaves become increasingly astringent with age. Flower buds and petals can be eaten raw in sandwiches, soups and salads. It is also used as a tea and as a vitamin supplement.
B. perennis has astringent properties and has been used in herbal medicine.
Daisies have traditionally been used for making daisy chains in children's games.
Daisy is used as a feminine name, and sometimes as a nickname for people named Margaret, after the French name for the oxeye daisy, marguerite.
The daisy is the national flower of the Netherlands.
Bellis perennis is a common European species of daisy, of the Asteraceae family, often considered the archetypal species of that name.
Many related plants also share the name "daisy", so to distinguish this species from other daisies it is sometimes qualified as common daisy, lawn daisy or English daisy. Historically, it has also been commonly known as bruisewort and occasionally woundwort (although the common name woundwort is now more closely associated with Stachys (woundworts)). Bellis perennis is native to western, central and northern Europe, but widely naturalised in most temperate regions including the Americas and Australasia.
It is an herbaceous perennial plant with short creeping rhizomes and rosettes of small rounded or spoon-shaped leaves that are from 3/4 to 2 inches (approx. 2–5 cm) long and grow flat to the ground. The species habitually colonises lawns, and is difficult to eradicate by mowing - hence the term 'lawn daisy'. Wherever it appears it is often considered an invasive weed.
The flowerheads are composite, in the form of a pseudanthium, consisting of many sessile flowers about 3/4 to 1-1/4 in (approx. 2–3 cm) in diameter, with white ray florets (often tipped red) and yellow disc florets. Each inflorescence is borne on single leafless stems 3/4 - 4 in (approx. 2–10 cm), rarely 6 in (approx. 15 cm) tall. The capitulum, or disc of florets, is surrounded by two rows of green bracts.
Centaurea is a genus of over 700 species of herbaceous thistle-like flowering plants in the family Asteraceae. Members of the genus are found only north of the equator, mostly in the Eastern Hemisphere; the Middle East and surrounding regions are particularly species-rich.
Knapweeds are robust weedy plants. Their leaves, spiny in some species, are usually deeply divided into elongated lobes at least in the plants' lower part, becoming entire towards the top. The "flowers" (actually pseudanthium inflorescences) are diverse in colour, ranging from intense blues, reds and yellows to any mixture of these and lighter shades towards white. Often, the disk flowers are much darker or lighter than the ray flowers, which also differ in morphology and are sterile. Each pseudanthium sits atop a cup- or basket-like cluster of scaly bracts, hence the name "basketflowers". Many species, in particular those inhabiting more arid regions, have a long and strong taproot.
Bellis perennis is a common European species of daisy, of the Asteraceae family, often considered the archetypal species of that name.
Many related plants also share the name "daisy", so to distinguish this species from other daisies it is sometimes qualified as common daisy, lawn daisy or English daisy. Historically, it has also been commonly known as bruisewort and occasionally woundwort (although the common name woundwort is now more closely associated with Stachys (woundworts)). Bellis perennis is native to western, central and northern Europe, but widely naturalised in most temperate regions including the Americas and Australasia.
Daisies, Bellis perennis
It is an herbaceous perennial plant with short creeping rhizomes and rosettes of small rounded or spoon-shaped leaves that are from 3/4 to 2 inches (approx. 2–5 cm) long and grow flat to the ground. The species habitually colonises lawns, and is difficult to eradicate by mowing - hence the term 'lawn daisy'. Wherever it appears it is often considered an invasive weed.
The flowerheads are composite, in the form of a pseudanthium, consisting of many sessile flowers about 3/4 to 1-1/4 in (approx. 2–3 cm) in diameter, with white ray florets (often tipped red) and yellow disc florets. Each inflorescence is borne on single leafless stems 3/4 - 4 in (approx. 2–10 cm), rarely 6 in (approx. 15 cm) tall. The capitulum, or disc of florets, is surrounded by two rows of green bracts known as "phyllaries".
Euphorbia (spurge) is a very large and diverse genus of flowering plants in the spurge family (Euphorbiaceae). Sometimes in ordinary English, "euphorbia" is used to refer to the entire Euphorbiaceae family (as the type genus), not just to members of the genus. Some euphorbias are well known and widely commercially available, such as Poinsettias at Christmas. Some are commonly cultivated as ornamentals, or collected and highly valued for the aesthetic appearance of their unique floral structures, such as the Crown of Thorns plant. Euphorbias from the deserts of Southern Africa and Madagascar have evolved physical characteristics and forms similar to cacti of North and South America, so they (along with various other kinds of plants) are often incorrectly referred to as "cacti", although they are far from being related as plants, see below. Some are used as ornamentals in landscaping, because of beautiful or striking overall forms, and drought and heat tolerance. Botanists may be fascinated by the diversity or bizarreness of some of the floral structures, and by the range of growth forms and adaptations to such a wide range of habitats.
Euphorbias range from tiny annual plants to large and long-lived trees. The genus has over or about 2,000 members,making it one of the largest genera of flowering plants. It also has one of the largest ranges of chromosome counts, along with Rumex and Senecio. Euphorbia antiquorum is the type species for the genus Euphorbia. It was first described by Carl Linnaeus in 1753 in Species Plantarum.
The plants share the feature of having a poisonous, milky, white latex-like sap, and unusual and unique kind of floral structures.The genus may be described by properties of its members' gene sequences, or by the shape and form (morphology) of its heads of flowers. When viewed as a whole, the head of flowers looks like a single flower (a pseudanthium). It has a unique kind of pseudanthium, called a cyathium, where each flower in the head is reduced to its barest essential part needed for sexual reproduction. The individual flowers are either male or female, with the male flowers reduced to only the stamen, and the females to the pistil.These flowers have no sepals, petals, or other parts that are typical of flowers in other kinds of plants. Structures supporting the flower head and beneath that have evolved to attract pollinators with nectar, and with shapes and colors that function the way petals and other flower parts do in other flowers. It is the only genus of plants that has all three kinds of photosynthesis, CAM, C3, and C4.
The genus can be found all over the world. The forms range from annual plants laying on the ground, to well developed tall trees. In deserts in Madagascar and southern Africa, convergent evolution has led to cactus-like forms where the plants occupy the same ecological niche as cacti do in deserts of North America and South America.The genus is primarily found in the tropical and subtropical regions of Africa and the Americas, but also in temperate zones worldwide. Succulent species originate mostly from Africa, the Americas and Madagascar.There exists a wide range of insular species.
Misidentification as cacti
Among laypersons, Euphorbias are among the most commonly confused plant taxa with cacti, especially the stem succulents. Euphorbias secrete a sticky, milky-white fluid with latex, but cacti do not. Individual flowers of Euphorbias are usually tiny and nondescript (although structures around the individual flowers may not be), without petals and sepals, unlike cacti, which often have fantastically showy flowers. Euphorbias from desert habitats with growth forms similar to cacti have thorns, which are different from the spines of cacti.
Etymology
The common name "spurge" derives from the Middle English/Old French espurge ("to purge"), due to the use of the plant's sap as a purgative. The botanical name Euphorbia derives from Euphorbos, the Greek physician of king Iuba (or Juba) II of Numidia (52–50 BC – 23 AD), who married the daughter of Anthony and Cleopatra. Juba was a prolific writer on various subjects, including natural history. Euphorbos wrote that one of the cactus-like Euphorbias (now called Euphorbia obtusifolia ssp. regis-jubae) which was used as a powerful laxative. In 12 B.C., Juba named this plant after his physician Euphorbos, as Augustus Caesar had dedicated a statue to the brother of Euphorbos, Antonius Musa, who was the personal physician of Augustus. In 1753, Botanist and taxonomist Carl Linnaeus assigned the name Euphorbia to the entire genus in the physician's honor.
Centaurea is a genus of over 700 species of herbaceous thistle-like flowering plants in the family Asteraceae. Members of the genus are found only north of the equator, mostly in the Eastern Hemisphere; the Middle East and surrounding regions are particularly species-rich. In the western United States, yellow starthistles are an invasive species. Around the year 1850, seeds from the plant had arrived to the state of California. It is believed that those seeds came from South America.
Common names
Common names for this genus are centaury, centory, starthistles, knapweeds, centaureas and the more ambiguous "bluets"; a vernacular name used for these plants in parts of England is "loggerheads" (common knapweed). The Plectocephalus group – possibly a distinct genus – is known as basketflowers. "Cornflower" is used for a few species, but that term more often specifically means either C. cyanus (the annual cornflower) or Centaurea montana (the perennial cornflower). The common name "centaury" is sometimes used, although this also refers to the unrelated plant genus Centaurium.
The name is said to be in reference to Chiron, the centaur of Greek mythology who discovered medicinal uses of a plant eventually called "centaury".
Description
Knapweeds are robust weedy plants. Their leaves, spiny in some species, are usually deeply divided into elongated lobes at least in the plants' lower part, becoming entire towards the top. The "flowers" (actually pseudanthium inflorescences) are diverse in colour, ranging from intense blues, reds and yellows to any mixture of these and lighter shades towards white. Often, the disk flowers are much darker or lighter than the ray flowers, which also differ in morphology and are sterile. Each pseudanthium sits atop a cup- or basket-like cluster of scaly bracts, hence the name "basketflowers". Many species, in particular those inhabiting more arid regions, have a long and strong taproot.
Certain knapweeds have a tendency to dominate large stretches of landscape together with a few other plants, typically one or two grasses and as many other large herbaceous plants. The common knapweed (C. nigra) for example is plentiful in the mesotrophic grasslands of England and nearby regions. It is most prominently found in pastures or meadows dominated by cock's-foot (Dactylis glomerata) as well as either of crested dog's-tail (Cynosurus cristatus) and false oat-grass (Arrhenatherum elatius). It is also often found in mesotrophic grassland on rendzinas and similar calcareous soils in association with glaucous sedge (Carex flacca), sheep's fescue (Festuca ovina), and either tor-grass (Brachypodium pinnatum) and rough hawkbit (Leontodon hispidus), or upright brome (Bromus erectus). In these grasslands, greater knapweed (C. scabiosa) is found much more rarely by comparison, often in association with red fescue (Festuca rubra) in addition to cock's-foot and false oat-grass.
Due to their habit of dominating ecosystems under good conditions, many Centaurea species can become invasive weeds in regions where they are not native. In parts of North America, diffuse knapweed (C. diffusa), spotted knapweed (C. maculosa) and yellow starthistle (C. solstitialis) cause severe problems in agriculture due to their uncontrolled spread. The seeds are typically transported by human traffic, in particular the tires of all-terrain vehicles. The two knapweeds are harmful mainly because they are strongly allelopathic, producing powerful toxins in their roots that stunt the growth of plants around them not adapted to this. Yellow starthistle, meanwhile, is inedible to most livestock due to its spines and apparently outright poisonous to horses and other equines. However, efficient methods of biological control by insect pests of these weeds have been developed; the knapweeds can also exploited to their detriment by targeted grazing. Controlled burning may also be used, though the timing is important to avoid the plants having seeded already, and neither allowing sufficient time for them to regrow from the rootstock.
Yet other species of Centaurea – mostly ones that occur between Italy and the Caucasus – are endemics of a single island or valley, and some of these are endangered. The Akamas Centaurea (Centaurea akamantis) of Cyprus is almost extinct, while the western Caucasus endemics C. leptophylla and C. straminicephala are at least very rare and C. hedgei and C. pecho from the same region are certainly not abundant either. The last four species would be adversely affected by the proposed Yusufeli Dam, which might actually destroy enough habitat to push the two rarer ones over the brink of extinction.
Centaurea are copious nectar producers, especially on high-lime soils. The high nectar yield of the genus makes it very attractive to insects such as butterflies – including the endangered Karner blue (Plebejus melissa samuelis) which visits introduced spotted knapweed – and day-flying moths – typically Zygaenidae, such as Zygaena loti or the six-spot burnet (Z. filipendulae). The larvae of some other Lepidoptera species use Centaurea species as food plants; see List of Lepidoptera that feed on Centaurea. Several of these are used in biological control of invasive knapweeds and starthistles.
Larvae of several true weevils (Curculionidae) of the subfamily Lixinae also feed on Centaurea. Some genera – such as Larinus whose larval food is flowerheads – have many species especially adapted to particular knapweeds or starthistle and are used in biological control too. These include the yellow starthistle flower weevil (L. curtus) for yellow starthistle, lesser knapweed flower weevil (L. minutus) for diffuse knapweed and blunt knapweed flower weevil (L. obtusus) for spotted knapweed. Broad-nosed seedhead weevil (Bangasternus fausti) larvae eat diffuse, spotted and squarrose knapweed (C. virgata ssp. squarrosa), while those of the yellow starthistle bud weevil (B. orientalis) do not seem to live on anything other than yellow starthistle and occasionally purple starthistle (C. calcitrapa). But perhaps most efficient in destroying developing yellow starthistle seedheads is the larva of the yellow starthistle hairy weevil (Eustenopus villosus). Knapweed root weevil (Cyphocleonus achates) larvae bore into the roots of spotted and to a lesser extentely diffuse knapweed, sometimes killing off the entire plant.
Also used in biological control are Tephritidae (peacock flies) whose larvae feed on Centaurea. Knapweed peacock fly (Chaetorellia acrolophi) larvae eat spotted knapweed and some other species. The yellow starthistle peacock fly (C. australis) has an initial generation each year which often uses cornflower (C. cyanus) as larval food; later generations switch to yellow starthistle. The flies are generally considered less efficient in destroying the growing seedheads than the weevils, but may be superior under certain conditions; employing flies and weevils in combination is expensive and does not noticeably increase their effect.
Use by humans
Although the genus may be considered by a quite significant number of relatively informed individuals to have an overall negative impact on human interests, particularly agricultural interests, the situation is not straightforward enough to simply declare the genus, or, at least, its most aggressively-spreading species, altogether negative. For instance, due to their moderate to high nectar production, which can occur over a comparatively long duration, many species of Centaurea are popular food sources for insects that may otherwise attack certain crops.[citation needed] It may be advisable for some types of farms to allow certain species in this genus, such as cornflower (C. cyanus) in a European setting, to grow adjacent to fields. Although they support and attract many types of beneficial life (not just beetles), these areas are known as beetle banks. When they are present, some pests may be drawn away from crops to them and predatory insects and arachnids that feed upon pest insects will be better-supported by these more naturalized areas. They additionally have the beneficial aspect of supporting pollinators, unlike many field crops such as maize. Moreover, being untreated with pesticides and providing more diversity, plants growing in more wild areas adjacent to farms produce more insects that attract and support birds which can also feed on pests that would harm crops. Insect production is especially high for beetle banks that have enough plants that serve in the role of host plant for immature insects, rather than just in the roles of adult food and/or shelter provision.
Some plants which are considered invasive or problematic in certain areas can have beneficial qualities that outweigh their negative qualities from a human and/or human agricultural point of view, although this sometimes requires some human management – particularly if adequate biological control has not been established for the more aggressive species. An example is wild parsnip, Pastinaca sativa, which produces florets that feed predatory (and other beneficial) insects as well as large tubular stems that provide winter shelter for native bees, wasps, and other organisms that can be beneficial for agriculture. The plant is considered invasive in some areas of the United States and is also often considered undesirable due to its ability to cause contact skin irritation. However, it also serves as a host plant for the black swallowtail butterfly, helps to bring nutrients up from soils with its deep taproot, and possesses evergreen foliage even in climate zones such as US zone 6. This foliage increases soil warmth and moisture which can be beneficial for certain types of life. Perhaps the most dramatic example of a generally disliked plant's beneficial qualities being usually overlooked is the often-despised ragwort, Jacobaea vulgaris, which topped the list by a large amount for nectar production in a UK study, with a production per floral unit of (2921 ± 448μg). This very high nectar production, coupled with its early blooming period, makes the plant helpful for the establishment of bee colonies in spring — a period that is often not well-served by commercial flower meadow seed mixes. It also has the situationally-beneficial quality of being a spring ephemeral, as well as an annual that lacks difficult-to-combat roots. Plants that provide necessary structural supports for invertebrate and small vertebrate predators can help to keep overall pest populations low.
The abundant nectar produced by C. solstitialis flowers attracts many pollinators. This is another reason for the success of the (situationally) highly invasive species. Due to genetic differences related to evolutionary adaption, not all members of Centaurea produce the same amount of nectar. Growing conditions, such as climate and soil, can have a very strong impact, even if the plants grow and flower. For instance, cornflower plants, Centaurea cyanus, produced 33% less seasonal nectar than Centaurea nigra in a UK study. C. nigra also ranked higher than ragwort in another UK study, although ragwort was still in the top 10 for yearly nectar production. The strong nectar production of certain members of the genus can be exploited to the farmer's advantage, possibly in combination with biological control. In particular, the yellow starthistle (C. solstitialis) as well as spotted knapweed (C. maculosa) are major honey plants for beekeepers. Monofloral honey from these plants is light and slightly tangy, and one of the finest honeys produced in the United States – due to its better availability, it is even fraudulently relabeled and sold as the scarce and expensive sourwood honey of the Appalachian Mountains. Placing beehives near stands of Centaurea will cause increased pollination. As most seedheads fail however when biocontrol pests have established themselves, the plants will bloom ever more abundantly in an attempt to replace the destroyed seedheads, to the point where they exhaust their resources in providing food for the pests (seeds), bees (pollen) and humans (honey). Output of allelopathic compounds is also liable to be reduced under such conditions – the plant has to compromise between allocating energy to reproduction and defense. This renders the weeds more likely to be suppressed by native vegetation or crops in the following years, especially if properly timed controlled burning[5] and/or targeted grazing by suitable livestock are also employed. While yellow starthistle and perhaps other species are toxic to equines, some other livestock may eat the non-spiny knapweeds with relish. In Europe, common knapweed (C. nigra) and globe knapweed (C. macrocephala) are locally important pollen sources for honeybees in mid-late summer.
8-Hydroxyquinoline has been identified as a main allelopathic compound produced by diffuse knapweed (C. diffusa); native North American plants are typically sensitive to it, while those of Eastern Europe and Asia Minor usually have coevolved with the knapweed and are little harmed if at all, aided by native microorganisms that break down or even feed on the abundantly secreted compound. Thus, 8-hydroxyquinoline is potentially useful to control American plants that have become invasive weeds in the diffuse knapweed's native range.
Arctiin, found in C. imperialis, has shown anticancer activity in laboratory studies. The roots of the long-lost C. foliosa, an endemic of Hatay Province (Turkey), are used in folk medicine, and other species are presumably too. A South Italian variety[verification needed] of the purple starthistle (C. calcitrapa) is traditionally consumed by ethnic Albanians (Arbëreshë people) in the Vulture area (southern Italy); e.g. in the Arbëreshë communities in Lucania the young whorls of C. calcitrapa are boiled and fried in mixtures with other weedy non-cultivated greens. According to research by the Michael Heinrich group at the Centre for Pharmacognosy and Phytotherapy (School of Pharmacy, University of London) "the antioxidant activity [...] of the young whorls of Centaurea calcitrapa, both in the DPPH and in the lipid peroxidation inhibition assays, [is] very interesting and [the] species should be investigated phytochemically and biochemically focusing on these properties". Extracts from C. calcitrapa were furthermore found to have significant xanthine oxidase (XO)-inhibiting activity.
Spotted knapweed as well as other species are rich in cnicin, a bitter compound found mainly in the leaves and often used to flavor the digestif amaro. In western Crete, Greece a local variety[verification needed] of C. calcitrapa called gourounaki (γουρουνάκι "little pig") also has its leaves eaten boiled by the locals. In the same island an endemic local species, C. idaea called katsoula (κατσούλα), tsita (τσίτα) or aspragatha (ασπραγκάθα), has its leaves eaten boiled by the locals too.
Some species are cultivated as ornamental plants in gardens. As regards other aspects of popular culture, cornflower (C. cyanus) is the floral emblem of Östergötland province (Sweden) – where is it called blåklint, literally "blue mountain" – and of Päijänne Tavastia region in Finland, where it is known as ruiskaunokki ("rye-beaks") or ruiskukka ("rye-flower"). It is also the national flower of Estonia where its local name rukkilill means "rye-lily", Belarus where it is called vałoška (Belarusian: валошка), and one of those of Germany where it is called Kornblume ("cornflower"). The origin of the name "caltrop" for the ancient low-tech area denial weapon is probably in some way connected with C. calcitrapa and its spiny seeds. This plant is attested to by the colloquial name "caltrop" at a time when the weapons were still called by their Roman name tribulus. Lastly, the color cornflower blue is named after C. cyanus. Cornflower is also used as a cut flower.
As namesake member of the subtribe Centaureinae of tribe Cardueae, the knapweeds are probably most closely related to genera such as Carthamus (distaff thistles), Cnicus (blessed thistle), Crupina (crupinas) or Notobasis (Syrian thistle), and somewhat less closely to most other thistles. The monotypic Cnicus seems in fact to properly belong in Centaurea.
Research in the late 20th century shows that Centaurea as traditionally defined is polyphyletic. A number of 19th- and 20th-century efforts to reorganize the genus were not successful, and it is not yet clear what the consequences of the recent research will be for classification of this genus and other related genera. The type species C. centaurium stands somewhat apart from the main lineage of knapweeds and thus the taxonomic consequences of a rearrangement might be severe, with hundreds of species needing to be moved to new genera. It has thus been proposed to change the type species to one of the main lineages to avoid this problem. What seems certain however is that the basketflowers – presently treated as a section Plectocephalus – will be reinstated as a distinct genus in the near future. The rock-centauries (Cheirolophus), formerly usually included in Centaurea, are now already treated as separate genus.
Better-known Centaurea species include:
Centaurea acaulis
Centaurea adpressa
Centaurea aegyptiaca
Centaurea aeolica
Centaurea aggregata
Centaurea akamantis – Akamas centaurea
Centaurea alba
Centaurea albonitens Turrill
Centaurea alpestris
Centaurea alpina
Centaurea ambigua
Centaurea amblyolepis
Centaurea americana – American basketflower, American starthistle
Centaurea ammocyanus
Centaurea antennata Dufour
Centaurea antiochia Boiss.
Centaurea aplolepa
Centaurea aplolepa subsp. carueliana
Centaurea appendicigera C.Koch
Centaurea argentea
Centaurea ascalonica
Centaurea aspera L. – rough starthistle
Centaurea atacamensis (Reiche) I.M.Johnst.
Centaurea atropurpurea
Centaurea ×aurata
Centaurea babylonica L.
Centaurea balsamita
Centaurea behen L. – ak behmen (Turkish)
Centaurea bella
Centaurea benedicta – Cnicus
Centaurea bieberseinii
Centaurea borjae
Centaurea bovina
Centaurea bracteata
Centaurea brevifimbriata Hub.-Mor.
Centaurea bulbosa
Centaurea busambarensis Guss.
Centaurea cachinalensis
Centaurea calcitrapa – purple starthistle, red starthistle, "caltrop"
Centaurea calcitrapoides
Centaurea cariensis Boiss.
Centaurea cariensiformis Hub.-Mor.
Centaurea caroli-henrici Gabrieljan & Dittrich
Centaurea centaurium L.
Centaurea chilensis
Centaurea cineraria – velvet centaurea, dusty miller
Centaurea clementei
Centaurea collina L.
Centaurea corymbosa
Centaurea crithmifolia
Centaurea crocodylium
Centaurea cyanoides J.Berggr. & Wahlenb.
Centaurea cyanus – cornflower, bachelor's button, boutonniere flower, hurtsickle, bluebottle, basketflower
Centaurea damascena
Centaurea debeauxii Gren. & Godr.
Centaurea demirizii Wagenitz
Centaurea depressa – low cornflower
Centaurea deusta
Centaurea diffusa – diffuse knapweed, white knapweed, tumble knapweed
Centaurea diluta – North African knapweed
Centaurea drabifolia Sm.
Centaurea drabifolioides Hub.-Mor.
Centaurea dschungarica
Centaurea emilae Hüseynova et Qaraxani[13]
Centaurea eriophora
Centaurea eryngioides
Centaurea filiformis
Centaurea fischeri Willd.
Centaurea floccosa
Centaurea foliosa Boiss. & Kotschy
Centaurea forojuliensis
Centaurea friderici Vis. – palagruška zečina (Croatian)
Centaurea gayana
Centaurea glaberrima Tausch
Centaurea glastifolia
Centaurea grinensis
Centaurea gymnocarpa
Centaurea haradjianii Wagenitz
Centaurea hedgei
Centaurea helenioides Boiss.
Centaurea hermannii F.Hermann
Centaurea horrida Badarò – fiordaliso spinoso (Italian)
Centaurea hyalolepis
Centaurea hypoleuca
Centaurea iberica – Iberian starthistle, Iberian knapweed
Centaurea idaea – katsoula, tsita (Cretan Greek)
Centaurea imperialis Hausskn. ex Bornm.
Centaurea jabukensis
Centaurea jacea – brown knapweed, brownray knapweed
Centaurea kasakorum
Centaurea kopetaghensis
Centaurea kotschyana Heuff.
Centaurea lanulata
Centaurea leptophylla
Centaurea leucophylla
Centaurea limbata
Centaurea lydia Boiss.
Centaurea macrocephala Puschk. ex Willd. – globe knapweed, Armenian basketflower
Centaurea maculosa – spotted knapweed (might belong in C. stoebe subsp. micranthos)
Centaurea mannagettae
Centaurea margaritalba Klok.
Centaurea marschalliana
Centaurea melitensis – Maltese starthistle; tocalote, tocolote (California)
Centaurea minor
Centaurea moschata – sweet sultan
Centaurea ×moncktonii C.E.Britton – meadow knapweed, protean knapweed (= C. ×pratensis Thuill non Salisb.)
Centaurea monocephala
Centaurea montana – montane knapweed, perennial cornflower, mountain cornflower, mountain bluet
Centaurea napifolia L. – fiordaliso romano (Italian)
Centaurea nervosa Rchb. ex Steud.
Centaurea nigra – common knapweed, black knapweed, lesser knapweed, hardheads
Centaurea nigrescens – Tyrol knapweed, short-fringed knapweed, Tyrol thistle
Centaurea nigrifimbria (C.Koch) Sosn.
Centaurea nivea (Bornm.) Wagenitz
Centaurea onopordifolia
Centaurea orientalis L.
Centaurea ornata Willd.
Centaurea ovina
Centaurea pallescens Delile
Centaurea paniculata L.
Centaurea parlatoris
Centaurea pecho
Centaurea phrygia – wig knapweed
Centaurea pindicola
Centaurea polypodiifolia
Centaurea ×pratensis Salisb. (C. jacea × C. nigra) – meadow knapweed
Centaurea procurrens
Centaurea ×psammogena G.Gayer. (C. diffusa × C. stoebe subsp. micranthos)
Centaurea pseudocaerulescens
Centaurea pseudophrygia C.A.Mey.
Centaurea pulcherrima Willd.
Centaurea pullata L.
Centaurea pumilio
Centaurea ragusina L.
Centaurea rigida
Centaurea rothrockii Greenm. – Mexican basketflower, Rothrock's basketflower, Rothrock's knapweed
Centaurea ruthenica
Centaurea rutifolia Sm.
Centaurea sadleriana – Pannonian knapweed
Centaurea salicifolia Bieb. ex Willd.
Centaurea scabiosa – greater knapweed
Centaurea scannensis
Centaurea scoparia
Centaurea scopulorum Boiss. & Heldr.
Centaurea seguenzae
Centaurea seridis L.
Centaurea sibirica
Centaurea simplicicaulis
Centaurea sinaica
Centaurea solstitialis – yellow starthistle, golden starthistle, yellow cockspur, St. Barnaby's thistle, Barnaby thistle
Centaurea speciosa
Centaurea sphaerocephala L.
Centaurea stenolepis
Centaurea stoebe L.
Centaurea stoebe subsp. micranthos (Gugler) Hayek
Centaurea straminicephala
Centaurea sulphurea – Sicilian starthistle
Centaurea tauromenitana Guss.
Centaurea tenoreana
Centaurea tommasinii
Centaurea transalpina Schleich. ex DC.
Centaurea tchihatcheffii — yanardöner (Turkish)
Centaurea trichocephala Bieb. ex Willd. – featherhead knapweed
Centaurea triniifolia
Centaurea triumfettii All.
Centaurea ucriae Lacaita
Centaurea uniflora Turra
Centaurea verbascifolia Vahl
Centaurea verutum L.
Centaurea virgata
Centaurea virgata subsp. squarrosa – squarrose knapweed
Centaurea wiedemanniana Fisch. & Mey.
Centaurea yozgatensis Wagenitz
Formerly placed here
Plant species placed in Centaurea in former times include:
Acroptilon repens – Russian knapweed (as C. repens)
Cheirolophus crassifolius – Maltese rock-centaury (as C. crassifolia, C. spathulata)
Femeniasia balearica (as C. balearica)
Volutaria muricata (as C. muricata)
en.wikipedia.org/wiki/Bellis_perennis
Bellis perennis is a common European species of daisy, of the Asteraceae family, often considered the archetypal species of that name.
Many related plants also share the name "daisy", so to distinguish this species from other daisies it is sometimes qualified as common daisy, lawn daisy or English daisy. Historically, it has also been commonly known as bruisewort and occasionally woundwort (although the common name woundwort is now more closely associated with Stachys (woundworts)). Bellis perennis is native to western, central and northern Europe, but widely naturalised in most temperate regions including the Americas[2][3] and Australasia.
Description
It is an herbaceous perennial plant with short creeping rhizomes and rosettes of small rounded or spoon-shaped leaves that are from 3/4 to 2 inches (approx. 2–5 cm) long and grow flat to the ground. The species habitually colonises lawns, and is difficult to eradicate by mowing - hence the term 'lawn daisy'. Wherever it appears it is often considered an invasive weed.[4]
The flowerheads are composite, in the form of a pseudanthium, consisting of many sessile flowers about 3/4 to 1-1/4 in (approx. 2–3 cm) in diameter, with white ray florets (often tipped red) and yellow disc florets. Each inflorescence is borne on single leafless stems 3/4 - 4 in (approx. 2–10 cm), rarely 6 in (approx. 15 cm) tall. The capitulum, or disc of florets, is surrounded by two rows of green bracts known as "phyllaries".[5]
Cultivation
B. perennis generally blooms from early to midsummer, although when grown under ideal conditions, they have a very long flowering season and will even produce a few flowers in the middle of mild winters.[6][7]
It can generally be grown in USDA Zones 4 - 8 (i.e. where minimum temperatures are above −30 °F (−34 °C)) in full sun to partial shade conditions, and requires low or no maintenance. It has no known serious insect or disease problems and can generally be grown in most well-drained soils. The plant may be propagated either by seed after the last frost, or by division after flowering.[6][8]
Though invasive, the species is still considered a valuable ground cover in certain garden settings (e.g., as part of English or cottage inspired gardens, as well as spring meadows where low growth and some color is desired in parallel with minimal care and maintenance while helping to crowd out noxious weeds once established and naturalised).
Numerous single- and double-flowered varieties are in cultivation, producing flat or spherical blooms in a range of sizes (1 cm to 6 cm) and colours (red, pink & white). They are generally grown from seed as biennial bedding plants. They can also be purchased as plugs in Spring. The cultivar 'Tasso series' has gained the Royal Horticultural Society's Award of Garden Merit.[9]
Etymology
Bellis is Latin for "pretty" and perennis is Latin for "everlasting".
The name "daisy" is considered a corruption of "day's eye",[10] because the whole head closes at night and opens in the morning. Chaucer called it "eye of the day". In Medieval times, Bellis perennis or the English Daisy was commonly known as "Mary's Rose".[11]
The English Daisy is also considered to be a flower of children and innocence.[12]
Daisy is used as a girl's name and as a nickname for girls named Margaret, after the French name for the oxeye daisy, marguerite.
Uses
Culinary
This daisy may be used as a potherb. Young leaves can be eaten raw in salads[13] or cooked, noting that the leaves become increasingly astringent with age.[6] Flower buds and petals can be eaten raw in sandwiches, soups and salads.[7] It is also used as a tea and as a vitamin supplement.[2]
Herbal medicine
Bellis perennis has astringent properties and has been used in herbal medicine.[14] In ancient Rome, the surgeons who accompanied Roman legions into battle would order their slaves to pick sacks full of daisies in order to extract their juice, hence the origin of this plant's scientific name in Latin. Bandages were soaked in this juice and would then be used to bind sword and spear cuts.
Bellis perennis is still used in homeopathy for wounds and after certain surgical procedures,[15][unreliable source?] as well as for blunt trauma in animals.[16][17][unreliable source?] Typically, the plant is harvested while in flower when intended for use in homeopathy.[7]
Bellis perennis flowers have been used in the traditional Austrian medicine internally as tea (or the leaves as a salad) for treatment of disorders of the gastrointestinal and respiratory tract.[18]
Other uses
Daisies have traditionally been used for making daisy chains in children's games.
Centaurea is a genus of over 700 species of herbaceous thistle-like flowering plants in the family Asteraceae. Members of the genus are found only north of the equator, mostly in the Eastern Hemisphere; the Middle East and surrounding regions are particularly species-rich. In the western United States, yellow starthistles are an invasive species. Around the year 1850, seeds from the plant had arrived to the state of California. It is believed that those seeds came from South America.
Common names
Common names for this genus are centaury, centory, starthistles, knapweeds, centaureas and the more ambiguous "bluets"; a vernacular name used for these plants in parts of England is "loggerheads" (common knapweed). The Plectocephalus group – possibly a distinct genus – is known as basketflowers. "Cornflower" is used for a few species, but that term more often specifically means either C. cyanus (the annual cornflower) or Centaurea montana (the perennial cornflower). The common name "centaury" is sometimes used, although this also refers to the unrelated plant genus Centaurium.
The name is said to be in reference to Chiron, the centaur of Greek mythology who discovered medicinal uses of a plant eventually called "centaury".
Description
Knapweeds are robust weedy plants. Their leaves, spiny in some species, are usually deeply divided into elongated lobes at least in the plants' lower part, becoming entire towards the top. The "flowers" (actually pseudanthium inflorescences) are diverse in colour, ranging from intense blues, reds and yellows to any mixture of these and lighter shades towards white. Often, the disk flowers are much darker or lighter than the ray flowers, which also differ in morphology and are sterile. Each pseudanthium sits atop a cup- or basket-like cluster of scaly bracts, hence the name "basketflowers". Many species, in particular those inhabiting more arid regions, have a long and strong taproot.
Certain knapweeds have a tendency to dominate large stretches of landscape together with a few other plants, typically one or two grasses and as many other large herbaceous plants. The common knapweed (C. nigra) for example is plentiful in the mesotrophic grasslands of England and nearby regions. It is most prominently found in pastures or meadows dominated by cock's-foot (Dactylis glomerata) as well as either of crested dog's-tail (Cynosurus cristatus) and false oat-grass (Arrhenatherum elatius). It is also often found in mesotrophic grassland on rendzinas and similar calcareous soils in association with glaucous sedge (Carex flacca), sheep's fescue (Festuca ovina), and either tor-grass (Brachypodium pinnatum) and rough hawkbit (Leontodon hispidus), or upright brome (Bromus erectus). In these grasslands, greater knapweed (C. scabiosa) is found much more rarely by comparison, often in association with red fescue (Festuca rubra) in addition to cock's-foot and false oat-grass.
Due to their habit of dominating ecosystems under good conditions, many Centaurea species can become invasive weeds in regions where they are not native. In parts of North America, diffuse knapweed (C. diffusa), spotted knapweed (C. maculosa) and yellow starthistle (C. solstitialis) cause severe problems in agriculture due to their uncontrolled spread. The seeds are typically transported by human traffic, in particular the tires of all-terrain vehicles. The two knapweeds are harmful mainly because they are strongly allelopathic, producing powerful toxins in their roots that stunt the growth of plants around them not adapted to this. Yellow starthistle, meanwhile, is inedible to most livestock due to its spines and apparently outright poisonous to horses and other equines. However, efficient methods of biological control by insect pests of these weeds have been developed; the knapweeds can also exploited to their detriment by targeted grazing. Controlled burning may also be used, though the timing is important to avoid the plants having seeded already, and neither allowing sufficient time for them to regrow from the rootstock.
Yet other species of Centaurea – mostly ones that occur between Italy and the Caucasus – are endemics of a single island or valley, and some of these are endangered. The Akamas Centaurea (Centaurea akamantis) of Cyprus is almost extinct, while the western Caucasus endemics C. leptophylla and C. straminicephala are at least very rare and C. hedgei and C. pecho from the same region are certainly not abundant either. The last four species would be adversely affected by the proposed Yusufeli Dam, which might actually destroy enough habitat to push the two rarer ones over the brink of extinction.
Centaurea are copious nectar producers, especially on high-lime soils. The high nectar yield of the genus makes it very attractive to insects such as butterflies – including the endangered Karner blue (Plebejus melissa samuelis) which visits introduced spotted knapweed – and day-flying moths – typically Zygaenidae, such as Zygaena loti or the six-spot burnet (Z. filipendulae). The larvae of some other Lepidoptera species use Centaurea species as food plants; see List of Lepidoptera that feed on Centaurea. Several of these are used in biological control of invasive knapweeds and starthistles.
Larvae of several true weevils (Curculionidae) of the subfamily Lixinae also feed on Centaurea. Some genera – such as Larinus whose larval food is flowerheads – have many species especially adapted to particular knapweeds or starthistle and are used in biological control too. These include the yellow starthistle flower weevil (L. curtus) for yellow starthistle, lesser knapweed flower weevil (L. minutus) for diffuse knapweed and blunt knapweed flower weevil (L. obtusus) for spotted knapweed. Broad-nosed seedhead weevil (Bangasternus fausti) larvae eat diffuse, spotted and squarrose knapweed (C. virgata ssp. squarrosa), while those of the yellow starthistle bud weevil (B. orientalis) do not seem to live on anything other than yellow starthistle and occasionally purple starthistle (C. calcitrapa). But perhaps most efficient in destroying developing yellow starthistle seedheads is the larva of the yellow starthistle hairy weevil (Eustenopus villosus). Knapweed root weevil (Cyphocleonus achates) larvae bore into the roots of spotted and to a lesser extentely diffuse knapweed, sometimes killing off the entire plant.
Also used in biological control are Tephritidae (peacock flies) whose larvae feed on Centaurea. Knapweed peacock fly (Chaetorellia acrolophi) larvae eat spotted knapweed and some other species. The yellow starthistle peacock fly (C. australis) has an initial generation each year which often uses cornflower (C. cyanus) as larval food; later generations switch to yellow starthistle. The flies are generally considered less efficient in destroying the growing seedheads than the weevils, but may be superior under certain conditions; employing flies and weevils in combination is expensive and does not noticeably increase their effect.
Use by humans
Although the genus may be considered by a quite significant number of relatively informed individuals to have an overall negative impact on human interests, particularly agricultural interests, the situation is not straightforward enough to simply declare the genus, or, at least, its most aggressively-spreading species, altogether negative. For instance, due to their moderate to high nectar production, which can occur over a comparatively long duration, many species of Centaurea are popular food sources for insects that may otherwise attack certain crops.[citation needed] It may be advisable for some types of farms to allow certain species in this genus, such as cornflower (C. cyanus) in a European setting, to grow adjacent to fields. Although they support and attract many types of beneficial life (not just beetles), these areas are known as beetle banks. When they are present, some pests may be drawn away from crops to them and predatory insects and arachnids that feed upon pest insects will be better-supported by these more naturalized areas. They additionally have the beneficial aspect of supporting pollinators, unlike many field crops such as maize. Moreover, being untreated with pesticides and providing more diversity, plants growing in more wild areas adjacent to farms produce more insects that attract and support birds which can also feed on pests that would harm crops. Insect production is especially high for beetle banks that have enough plants that serve in the role of host plant for immature insects, rather than just in the roles of adult food and/or shelter provision.
Some plants which are considered invasive or problematic in certain areas can have beneficial qualities that outweigh their negative qualities from a human and/or human agricultural point of view, although this sometimes requires some human management – particularly if adequate biological control has not been established for the more aggressive species. An example is wild parsnip, Pastinaca sativa, which produces florets that feed predatory (and other beneficial) insects as well as large tubular stems that provide winter shelter for native bees, wasps, and other organisms that can be beneficial for agriculture. The plant is considered invasive in some areas of the United States and is also often considered undesirable due to its ability to cause contact skin irritation. However, it also serves as a host plant for the black swallowtail butterfly, helps to bring nutrients up from soils with its deep taproot, and possesses evergreen foliage even in climate zones such as US zone 6. This foliage increases soil warmth and moisture which can be beneficial for certain types of life. Perhaps the most dramatic example of a generally disliked plant's beneficial qualities being usually overlooked is the often-despised ragwort, Jacobaea vulgaris, which topped the list by a large amount for nectar production in a UK study, with a production per floral unit of (2921 ± 448μg). This very high nectar production, coupled with its early blooming period, makes the plant helpful for the establishment of bee colonies in spring — a period that is often not well-served by commercial flower meadow seed mixes. It also has the situationally-beneficial quality of being a spring ephemeral, as well as an annual that lacks difficult-to-combat roots. Plants that provide necessary structural supports for invertebrate and small vertebrate predators can help to keep overall pest populations low.
The abundant nectar produced by C. solstitialis flowers attracts many pollinators. This is another reason for the success of the (situationally) highly invasive species. Due to genetic differences related to evolutionary adaption, not all members of Centaurea produce the same amount of nectar. Growing conditions, such as climate and soil, can have a very strong impact, even if the plants grow and flower. For instance, cornflower plants, Centaurea cyanus, produced 33% less seasonal nectar than Centaurea nigra in a UK study. C. nigra also ranked higher than ragwort in another UK study, although ragwort was still in the top 10 for yearly nectar production. The strong nectar production of certain members of the genus can be exploited to the farmer's advantage, possibly in combination with biological control. In particular, the yellow starthistle (C. solstitialis) as well as spotted knapweed (C. maculosa) are major honey plants for beekeepers. Monofloral honey from these plants is light and slightly tangy, and one of the finest honeys produced in the United States – due to its better availability, it is even fraudulently relabeled and sold as the scarce and expensive sourwood honey of the Appalachian Mountains. Placing beehives near stands of Centaurea will cause increased pollination. As most seedheads fail however when biocontrol pests have established themselves, the plants will bloom ever more abundantly in an attempt to replace the destroyed seedheads, to the point where they exhaust their resources in providing food for the pests (seeds), bees (pollen) and humans (honey). Output of allelopathic compounds is also liable to be reduced under such conditions – the plant has to compromise between allocating energy to reproduction and defense. This renders the weeds more likely to be suppressed by native vegetation or crops in the following years, especially if properly timed controlled burning[5] and/or targeted grazing by suitable livestock are also employed. While yellow starthistle and perhaps other species are toxic to equines, some other livestock may eat the non-spiny knapweeds with relish. In Europe, common knapweed (C. nigra) and globe knapweed (C. macrocephala) are locally important pollen sources for honeybees in mid-late summer.
8-Hydroxyquinoline has been identified as a main allelopathic compound produced by diffuse knapweed (C. diffusa); native North American plants are typically sensitive to it, while those of Eastern Europe and Asia Minor usually have coevolved with the knapweed and are little harmed if at all, aided by native microorganisms that break down or even feed on the abundantly secreted compound. Thus, 8-hydroxyquinoline is potentially useful to control American plants that have become invasive weeds in the diffuse knapweed's native range.
Arctiin, found in C. imperialis, has shown anticancer activity in laboratory studies. The roots of the long-lost C. foliosa, an endemic of Hatay Province (Turkey), are used in folk medicine, and other species are presumably too. A South Italian variety[verification needed] of the purple starthistle (C. calcitrapa) is traditionally consumed by ethnic Albanians (Arbëreshë people) in the Vulture area (southern Italy); e.g. in the Arbëreshë communities in Lucania the young whorls of C. calcitrapa are boiled and fried in mixtures with other weedy non-cultivated greens. According to research by the Michael Heinrich group at the Centre for Pharmacognosy and Phytotherapy (School of Pharmacy, University of London) "the antioxidant activity [...] of the young whorls of Centaurea calcitrapa, both in the DPPH and in the lipid peroxidation inhibition assays, [is] very interesting and [the] species should be investigated phytochemically and biochemically focusing on these properties". Extracts from C. calcitrapa were furthermore found to have significant xanthine oxidase (XO)-inhibiting activity.
Spotted knapweed as well as other species are rich in cnicin, a bitter compound found mainly in the leaves and often used to flavor the digestif amaro. In western Crete, Greece a local variety[verification needed] of C. calcitrapa called gourounaki (γουρουνάκι "little pig") also has its leaves eaten boiled by the locals. In the same island an endemic local species, C. idaea called katsoula (κατσούλα), tsita (τσίτα) or aspragatha (ασπραγκάθα), has its leaves eaten boiled by the locals too.
Some species are cultivated as ornamental plants in gardens. As regards other aspects of popular culture, cornflower (C. cyanus) is the floral emblem of Östergötland province (Sweden) – where is it called blåklint, literally "blue mountain" – and of Päijänne Tavastia region in Finland, where it is known as ruiskaunokki ("rye-beaks") or ruiskukka ("rye-flower"). It is also the national flower of Estonia where its local name rukkilill means "rye-lily", Belarus where it is called vałoška (Belarusian: валошка), and one of those of Germany where it is called Kornblume ("cornflower"). The origin of the name "caltrop" for the ancient low-tech area denial weapon is probably in some way connected with C. calcitrapa and its spiny seeds. This plant is attested to by the colloquial name "caltrop" at a time when the weapons were still called by their Roman name tribulus. Lastly, the color cornflower blue is named after C. cyanus. Cornflower is also used as a cut flower.
As namesake member of the subtribe Centaureinae of tribe Cardueae, the knapweeds are probably most closely related to genera such as Carthamus (distaff thistles), Cnicus (blessed thistle), Crupina (crupinas) or Notobasis (Syrian thistle), and somewhat less closely to most other thistles. The monotypic Cnicus seems in fact to properly belong in Centaurea.
Research in the late 20th century shows that Centaurea as traditionally defined is polyphyletic. A number of 19th- and 20th-century efforts to reorganize the genus were not successful, and it is not yet clear what the consequences of the recent research will be for classification of this genus and other related genera. The type species C. centaurium stands somewhat apart from the main lineage of knapweeds and thus the taxonomic consequences of a rearrangement might be severe, with hundreds of species needing to be moved to new genera. It has thus been proposed to change the type species to one of the main lineages to avoid this problem. What seems certain however is that the basketflowers – presently treated as a section Plectocephalus – will be reinstated as a distinct genus in the near future. The rock-centauries (Cheirolophus), formerly usually included in Centaurea, are now already treated as separate genus.
Better-known Centaurea species include:
Centaurea acaulis
Centaurea adpressa
Centaurea aegyptiaca
Centaurea aeolica
Centaurea aggregata
Centaurea akamantis – Akamas centaurea
Centaurea alba
Centaurea albonitens Turrill
Centaurea alpestris
Centaurea alpina
Centaurea ambigua
Centaurea amblyolepis
Centaurea americana – American basketflower, American starthistle
Centaurea ammocyanus
Centaurea antennata Dufour
Centaurea antiochia Boiss.
Centaurea aplolepa
Centaurea aplolepa subsp. carueliana
Centaurea appendicigera C.Koch
Centaurea argentea
Centaurea ascalonica
Centaurea aspera L. – rough starthistle
Centaurea atacamensis (Reiche) I.M.Johnst.
Centaurea atropurpurea
Centaurea ×aurata
Centaurea babylonica L.
Centaurea balsamita
Centaurea behen L. – ak behmen (Turkish)
Centaurea bella
Centaurea benedicta – Cnicus
Centaurea bieberseinii
Centaurea borjae
Centaurea bovina
Centaurea bracteata
Centaurea brevifimbriata Hub.-Mor.
Centaurea bulbosa
Centaurea busambarensis Guss.
Centaurea cachinalensis
Centaurea calcitrapa – purple starthistle, red starthistle, "caltrop"
Centaurea calcitrapoides
Centaurea cariensis Boiss.
Centaurea cariensiformis Hub.-Mor.
Centaurea caroli-henrici Gabrieljan & Dittrich
Centaurea centaurium L.
Centaurea chilensis
Centaurea cineraria – velvet centaurea, dusty miller
Centaurea clementei
Centaurea collina L.
Centaurea corymbosa
Centaurea crithmifolia
Centaurea crocodylium
Centaurea cyanoides J.Berggr. & Wahlenb.
Centaurea cyanus – cornflower, bachelor's button, boutonniere flower, hurtsickle, bluebottle, basketflower
Centaurea damascena
Centaurea debeauxii Gren. & Godr.
Centaurea demirizii Wagenitz
Centaurea depressa – low cornflower
Centaurea deusta
Centaurea diffusa – diffuse knapweed, white knapweed, tumble knapweed
Centaurea diluta – North African knapweed
Centaurea drabifolia Sm.
Centaurea drabifolioides Hub.-Mor.
Centaurea dschungarica
Centaurea emilae Hüseynova et Qaraxani[13]
Centaurea eriophora
Centaurea eryngioides
Centaurea filiformis
Centaurea fischeri Willd.
Centaurea floccosa
Centaurea foliosa Boiss. & Kotschy
Centaurea forojuliensis
Centaurea friderici Vis. – palagruška zečina (Croatian)
Centaurea gayana
Centaurea glaberrima Tausch
Centaurea glastifolia
Centaurea grinensis
Centaurea gymnocarpa
Centaurea haradjianii Wagenitz
Centaurea hedgei
Centaurea helenioides Boiss.
Centaurea hermannii F.Hermann
Centaurea horrida Badarò – fiordaliso spinoso (Italian)
Centaurea hyalolepis
Centaurea hypoleuca
Centaurea iberica – Iberian starthistle, Iberian knapweed
Centaurea idaea – katsoula, tsita (Cretan Greek)
Centaurea imperialis Hausskn. ex Bornm.
Centaurea jabukensis
Centaurea jacea – brown knapweed, brownray knapweed
Centaurea kasakorum
Centaurea kopetaghensis
Centaurea kotschyana Heuff.
Centaurea lanulata
Centaurea leptophylla
Centaurea leucophylla
Centaurea limbata
Centaurea lydia Boiss.
Centaurea macrocephala Puschk. ex Willd. – globe knapweed, Armenian basketflower
Centaurea maculosa – spotted knapweed (might belong in C. stoebe subsp. micranthos)
Centaurea mannagettae
Centaurea margaritalba Klok.
Centaurea marschalliana
Centaurea melitensis – Maltese starthistle; tocalote, tocolote (California)
Centaurea minor
Centaurea moschata – sweet sultan
Centaurea ×moncktonii C.E.Britton – meadow knapweed, protean knapweed (= C. ×pratensis Thuill non Salisb.)
Centaurea monocephala
Centaurea montana – montane knapweed, perennial cornflower, mountain cornflower, mountain bluet
Centaurea napifolia L. – fiordaliso romano (Italian)
Centaurea nervosa Rchb. ex Steud.
Centaurea nigra – common knapweed, black knapweed, lesser knapweed, hardheads
Centaurea nigrescens – Tyrol knapweed, short-fringed knapweed, Tyrol thistle
Centaurea nigrifimbria (C.Koch) Sosn.
Centaurea nivea (Bornm.) Wagenitz
Centaurea onopordifolia
Centaurea orientalis L.
Centaurea ornata Willd.
Centaurea ovina
Centaurea pallescens Delile
Centaurea paniculata L.
Centaurea parlatoris
Centaurea pecho
Centaurea phrygia – wig knapweed
Centaurea pindicola
Centaurea polypodiifolia
Centaurea ×pratensis Salisb. (C. jacea × C. nigra) – meadow knapweed
Centaurea procurrens
Centaurea ×psammogena G.Gayer. (C. diffusa × C. stoebe subsp. micranthos)
Centaurea pseudocaerulescens
Centaurea pseudophrygia C.A.Mey.
Centaurea pulcherrima Willd.
Centaurea pullata L.
Centaurea pumilio
Centaurea ragusina L.
Centaurea rigida
Centaurea rothrockii Greenm. – Mexican basketflower, Rothrock's basketflower, Rothrock's knapweed
Centaurea ruthenica
Centaurea rutifolia Sm.
Centaurea sadleriana – Pannonian knapweed
Centaurea salicifolia Bieb. ex Willd.
Centaurea scabiosa – greater knapweed
Centaurea scannensis
Centaurea scoparia
Centaurea scopulorum Boiss. & Heldr.
Centaurea seguenzae
Centaurea seridis L.
Centaurea sibirica
Centaurea simplicicaulis
Centaurea sinaica
Centaurea solstitialis – yellow starthistle, golden starthistle, yellow cockspur, St. Barnaby's thistle, Barnaby thistle
Centaurea speciosa
Centaurea sphaerocephala L.
Centaurea stenolepis
Centaurea stoebe L.
Centaurea stoebe subsp. micranthos (Gugler) Hayek
Centaurea straminicephala
Centaurea sulphurea – Sicilian starthistle
Centaurea tauromenitana Guss.
Centaurea tenoreana
Centaurea tommasinii
Centaurea transalpina Schleich. ex DC.
Centaurea tchihatcheffii — yanardöner (Turkish)
Centaurea trichocephala Bieb. ex Willd. – featherhead knapweed
Centaurea triniifolia
Centaurea triumfettii All.
Centaurea ucriae Lacaita
Centaurea uniflora Turra
Centaurea verbascifolia Vahl
Centaurea verutum L.
Centaurea virgata
Centaurea virgata subsp. squarrosa – squarrose knapweed
Centaurea wiedemanniana Fisch. & Mey.
Centaurea yozgatensis Wagenitz
Formerly placed here
Plant species placed in Centaurea in former times include:
Acroptilon repens – Russian knapweed (as C. repens)
Cheirolophus crassifolius – Maltese rock-centaury (as C. crassifolia, C. spathulata)
Femeniasia balearica (as C. balearica)
Volutaria muricata (as C. muricata)
Hoverfly on Knapweed
Hoverflies, sometimes called flower flies or syrphid flies, make up the insect family Syrphidae. As their common name suggests, they are often seen hovering or nectaring at flowers; the adults of many species feed mainly on nectar and pollen, while the larvae (maggots) eat a wide range of foods. In some species, the larvae are saprotrophs, eating decaying plant and animal matter in the soil or in ponds and streams. In other species, the larvae are insectivores and prey on aphids, thrips, and other plant-sucking insects.
Knapweeds are robust weedy plants. Their leaves, spiny in some species, are usually deeply divided into elongated lobes at least in the plants' lower part, becoming entire towards the top. The "flowers" (actually pseudanthium inflorescences) are diverse in colour, ranging from intense blues, reds and yellows to any mixture of these and lighter shades towards white
The Asteraceae or Compositae, the aster, daisy, or sunflower family, is the second largest family of flowering plants, in terms of number of species.
The name Asteraceae is derived from the type genus Aster, while Compositae, an older but still valid
name, means composite and refers to the characteristic inflorescence, a special type of pseudanthium found in only a few other angiosperm families. The study of this family is known as synantherology.
According to the Royal Botanic Gardens of Kew, the family comprises more than 1,600 genera and 23,000 species. The largest genera are Senecio (1,500 species), Vernonia (1,000 species), Cousinia (600 species) and Centaurea (600 species). The circumscription of the genera is often problematic and some of these have been frequently divided into minor subgroups.
Asteraceae are cosmopolitan, but are most common in temperate regions and tropical mountains.
Reference: Wikipedia
Centaurea is a genus of over 700 species of herbaceous thistle-like flowering plants in the family Asteraceae. Members of the genus are found only north of the equator, mostly in the Eastern Hemisphere; the Middle East and surrounding regions are particularly species-rich. In the western United States, yellow starthistles are an invasive species. Around the year 1850, seeds from the plant had arrived to the state of California. It is believed that those seeds came from South America.
Common names
Common names for this genus are centaury, centory, starthistles, knapweeds, centaureas and the more ambiguous "bluets"; a vernacular name used for these plants in parts of England is "loggerheads" (common knapweed). The Plectocephalus group – possibly a distinct genus – is known as basketflowers. "Cornflower" is used for a few species, but that term more often specifically means either C. cyanus (the annual cornflower) or Centaurea montana (the perennial cornflower). The common name "centaury" is sometimes used, although this also refers to the unrelated plant genus Centaurium.
The name is said to be in reference to Chiron, the centaur of Greek mythology who discovered medicinal uses of a plant eventually called "centaury".
Description
Knapweeds are robust weedy plants. Their leaves, spiny in some species, are usually deeply divided into elongated lobes at least in the plants' lower part, becoming entire towards the top. The "flowers" (actually pseudanthium inflorescences) are diverse in colour, ranging from intense blues, reds and yellows to any mixture of these and lighter shades towards white. Often, the disk flowers are much darker or lighter than the ray flowers, which also differ in morphology and are sterile. Each pseudanthium sits atop a cup- or basket-like cluster of scaly bracts, hence the name "basketflowers". Many species, in particular those inhabiting more arid regions, have a long and strong taproot.
Certain knapweeds have a tendency to dominate large stretches of landscape together with a few other plants, typically one or two grasses and as many other large herbaceous plants. The common knapweed (C. nigra) for example is plentiful in the mesotrophic grasslands of England and nearby regions. It is most prominently found in pastures or meadows dominated by cock's-foot (Dactylis glomerata) as well as either of crested dog's-tail (Cynosurus cristatus) and false oat-grass (Arrhenatherum elatius). It is also often found in mesotrophic grassland on rendzinas and similar calcareous soils in association with glaucous sedge (Carex flacca), sheep's fescue (Festuca ovina), and either tor-grass (Brachypodium pinnatum) and rough hawkbit (Leontodon hispidus), or upright brome (Bromus erectus). In these grasslands, greater knapweed (C. scabiosa) is found much more rarely by comparison, often in association with red fescue (Festuca rubra) in addition to cock's-foot and false oat-grass.
Due to their habit of dominating ecosystems under good conditions, many Centaurea species can become invasive weeds in regions where they are not native. In parts of North America, diffuse knapweed (C. diffusa), spotted knapweed (C. maculosa) and yellow starthistle (C. solstitialis) cause severe problems in agriculture due to their uncontrolled spread. The seeds are typically transported by human traffic, in particular the tires of all-terrain vehicles. The two knapweeds are harmful mainly because they are strongly allelopathic, producing powerful toxins in their roots that stunt the growth of plants around them not adapted to this. Yellow starthistle, meanwhile, is inedible to most livestock due to its spines and apparently outright poisonous to horses and other equines. However, efficient methods of biological control by insect pests of these weeds have been developed; the knapweeds can also exploited to their detriment by targeted grazing. Controlled burning may also be used, though the timing is important to avoid the plants having seeded already, and neither allowing sufficient time for them to regrow from the rootstock.
Yet other species of Centaurea – mostly ones that occur between Italy and the Caucasus – are endemics of a single island or valley, and some of these are endangered. The Akamas Centaurea (Centaurea akamantis) of Cyprus is almost extinct, while the western Caucasus endemics C. leptophylla and C. straminicephala are at least very rare and C. hedgei and C. pecho from the same region are certainly not abundant either. The last four species would be adversely affected by the proposed Yusufeli Dam, which might actually destroy enough habitat to push the two rarer ones over the brink of extinction.
Centaurea are copious nectar producers, especially on high-lime soils. The high nectar yield of the genus makes it very attractive to insects such as butterflies – including the endangered Karner blue (Plebejus melissa samuelis) which visits introduced spotted knapweed – and day-flying moths – typically Zygaenidae, such as Zygaena loti or the six-spot burnet (Z. filipendulae). The larvae of some other Lepidoptera species use Centaurea species as food plants; see List of Lepidoptera that feed on Centaurea. Several of these are used in biological control of invasive knapweeds and starthistles.
Larvae of several true weevils (Curculionidae) of the subfamily Lixinae also feed on Centaurea. Some genera – such as Larinus whose larval food is flowerheads – have many species especially adapted to particular knapweeds or starthistle and are used in biological control too. These include the yellow starthistle flower weevil (L. curtus) for yellow starthistle, lesser knapweed flower weevil (L. minutus) for diffuse knapweed and blunt knapweed flower weevil (L. obtusus) for spotted knapweed. Broad-nosed seedhead weevil (Bangasternus fausti) larvae eat diffuse, spotted and squarrose knapweed (C. virgata ssp. squarrosa), while those of the yellow starthistle bud weevil (B. orientalis) do not seem to live on anything other than yellow starthistle and occasionally purple starthistle (C. calcitrapa). But perhaps most efficient in destroying developing yellow starthistle seedheads is the larva of the yellow starthistle hairy weevil (Eustenopus villosus). Knapweed root weevil (Cyphocleonus achates) larvae bore into the roots of spotted and to a lesser extentely diffuse knapweed, sometimes killing off the entire plant.
Also used in biological control are Tephritidae (peacock flies) whose larvae feed on Centaurea. Knapweed peacock fly (Chaetorellia acrolophi) larvae eat spotted knapweed and some other species. The yellow starthistle peacock fly (C. australis) has an initial generation each year which often uses cornflower (C. cyanus) as larval food; later generations switch to yellow starthistle. The flies are generally considered less efficient in destroying the growing seedheads than the weevils, but may be superior under certain conditions; employing flies and weevils in combination is expensive and does not noticeably increase their effect.
Use by humans
Although the genus may be considered by a quite significant number of relatively informed individuals to have an overall negative impact on human interests, particularly agricultural interests, the situation is not straightforward enough to simply declare the genus, or, at least, its most aggressively-spreading species, altogether negative. For instance, due to their moderate to high nectar production, which can occur over a comparatively long duration, many species of Centaurea are popular food sources for insects that may otherwise attack certain crops.[citation needed] It may be advisable for some types of farms to allow certain species in this genus, such as cornflower (C. cyanus) in a European setting, to grow adjacent to fields. Although they support and attract many types of beneficial life (not just beetles), these areas are known as beetle banks. When they are present, some pests may be drawn away from crops to them and predatory insects and arachnids that feed upon pest insects will be better-supported by these more naturalized areas. They additionally have the beneficial aspect of supporting pollinators, unlike many field crops such as maize. Moreover, being untreated with pesticides and providing more diversity, plants growing in more wild areas adjacent to farms produce more insects that attract and support birds which can also feed on pests that would harm crops. Insect production is especially high for beetle banks that have enough plants that serve in the role of host plant for immature insects, rather than just in the roles of adult food and/or shelter provision.
Some plants which are considered invasive or problematic in certain areas can have beneficial qualities that outweigh their negative qualities from a human and/or human agricultural point of view, although this sometimes requires some human management – particularly if adequate biological control has not been established for the more aggressive species. An example is wild parsnip, Pastinaca sativa, which produces florets that feed predatory (and other beneficial) insects as well as large tubular stems that provide winter shelter for native bees, wasps, and other organisms that can be beneficial for agriculture. The plant is considered invasive in some areas of the United States and is also often considered undesirable due to its ability to cause contact skin irritation. However, it also serves as a host plant for the black swallowtail butterfly, helps to bring nutrients up from soils with its deep taproot, and possesses evergreen foliage even in climate zones such as US zone 6. This foliage increases soil warmth and moisture which can be beneficial for certain types of life. Perhaps the most dramatic example of a generally disliked plant's beneficial qualities being usually overlooked is the often-despised ragwort, Jacobaea vulgaris, which topped the list by a large amount for nectar production in a UK study, with a production per floral unit of (2921 ± 448μg). This very high nectar production, coupled with its early blooming period, makes the plant helpful for the establishment of bee colonies in spring — a period that is often not well-served by commercial flower meadow seed mixes. It also has the situationally-beneficial quality of being a spring ephemeral, as well as an annual that lacks difficult-to-combat roots. Plants that provide necessary structural supports for invertebrate and small vertebrate predators can help to keep overall pest populations low.
The abundant nectar produced by C. solstitialis flowers attracts many pollinators. This is another reason for the success of the (situationally) highly invasive species. Due to genetic differences related to evolutionary adaption, not all members of Centaurea produce the same amount of nectar. Growing conditions, such as climate and soil, can have a very strong impact, even if the plants grow and flower. For instance, cornflower plants, Centaurea cyanus, produced 33% less seasonal nectar than Centaurea nigra in a UK study. C. nigra also ranked higher than ragwort in another UK study, although ragwort was still in the top 10 for yearly nectar production. The strong nectar production of certain members of the genus can be exploited to the farmer's advantage, possibly in combination with biological control. In particular, the yellow starthistle (C. solstitialis) as well as spotted knapweed (C. maculosa) are major honey plants for beekeepers. Monofloral honey from these plants is light and slightly tangy, and one of the finest honeys produced in the United States – due to its better availability, it is even fraudulently relabeled and sold as the scarce and expensive sourwood honey of the Appalachian Mountains. Placing beehives near stands of Centaurea will cause increased pollination. As most seedheads fail however when biocontrol pests have established themselves, the plants will bloom ever more abundantly in an attempt to replace the destroyed seedheads, to the point where they exhaust their resources in providing food for the pests (seeds), bees (pollen) and humans (honey). Output of allelopathic compounds is also liable to be reduced under such conditions – the plant has to compromise between allocating energy to reproduction and defense. This renders the weeds more likely to be suppressed by native vegetation or crops in the following years, especially if properly timed controlled burning[5] and/or targeted grazing by suitable livestock are also employed. While yellow starthistle and perhaps other species are toxic to equines, some other livestock may eat the non-spiny knapweeds with relish. In Europe, common knapweed (C. nigra) and globe knapweed (C. macrocephala) are locally important pollen sources for honeybees in mid-late summer.
8-Hydroxyquinoline has been identified as a main allelopathic compound produced by diffuse knapweed (C. diffusa); native North American plants are typically sensitive to it, while those of Eastern Europe and Asia Minor usually have coevolved with the knapweed and are little harmed if at all, aided by native microorganisms that break down or even feed on the abundantly secreted compound. Thus, 8-hydroxyquinoline is potentially useful to control American plants that have become invasive weeds in the diffuse knapweed's native range.
Arctiin, found in C. imperialis, has shown anticancer activity in laboratory studies. The roots of the long-lost C. foliosa, an endemic of Hatay Province (Turkey), are used in folk medicine, and other species are presumably too. A South Italian variety[verification needed] of the purple starthistle (C. calcitrapa) is traditionally consumed by ethnic Albanians (Arbëreshë people) in the Vulture area (southern Italy); e.g. in the Arbëreshë communities in Lucania the young whorls of C. calcitrapa are boiled and fried in mixtures with other weedy non-cultivated greens. According to research by the Michael Heinrich group at the Centre for Pharmacognosy and Phytotherapy (School of Pharmacy, University of London) "the antioxidant activity [...] of the young whorls of Centaurea calcitrapa, both in the DPPH and in the lipid peroxidation inhibition assays, [is] very interesting and [the] species should be investigated phytochemically and biochemically focusing on these properties". Extracts from C. calcitrapa were furthermore found to have significant xanthine oxidase (XO)-inhibiting activity.
Spotted knapweed as well as other species are rich in cnicin, a bitter compound found mainly in the leaves and often used to flavor the digestif amaro. In western Crete, Greece a local variety[verification needed] of C. calcitrapa called gourounaki (γουρουνάκι "little pig") also has its leaves eaten boiled by the locals. In the same island an endemic local species, C. idaea called katsoula (κατσούλα), tsita (τσίτα) or aspragatha (ασπραγκάθα), has its leaves eaten boiled by the locals too.
Some species are cultivated as ornamental plants in gardens. As regards other aspects of popular culture, cornflower (C. cyanus) is the floral emblem of Östergötland province (Sweden) – where is it called blåklint, literally "blue mountain" – and of Päijänne Tavastia region in Finland, where it is known as ruiskaunokki ("rye-beaks") or ruiskukka ("rye-flower"). It is also the national flower of Estonia where its local name rukkilill means "rye-lily", Belarus where it is called vałoška (Belarusian: валошка), and one of those of Germany where it is called Kornblume ("cornflower"). The origin of the name "caltrop" for the ancient low-tech area denial weapon is probably in some way connected with C. calcitrapa and its spiny seeds. This plant is attested to by the colloquial name "caltrop" at a time when the weapons were still called by their Roman name tribulus. Lastly, the color cornflower blue is named after C. cyanus. Cornflower is also used as a cut flower.
As namesake member of the subtribe Centaureinae of tribe Cardueae, the knapweeds are probably most closely related to genera such as Carthamus (distaff thistles), Cnicus (blessed thistle), Crupina (crupinas) or Notobasis (Syrian thistle), and somewhat less closely to most other thistles. The monotypic Cnicus seems in fact to properly belong in Centaurea.
Research in the late 20th century shows that Centaurea as traditionally defined is polyphyletic. A number of 19th- and 20th-century efforts to reorganize the genus were not successful, and it is not yet clear what the consequences of the recent research will be for classification of this genus and other related genera. The type species C. centaurium stands somewhat apart from the main lineage of knapweeds and thus the taxonomic consequences of a rearrangement might be severe, with hundreds of species needing to be moved to new genera. It has thus been proposed to change the type species to one of the main lineages to avoid this problem. What seems certain however is that the basketflowers – presently treated as a section Plectocephalus – will be reinstated as a distinct genus in the near future. The rock-centauries (Cheirolophus), formerly usually included in Centaurea, are now already treated as separate genus.
Better-known Centaurea species include:
Centaurea acaulis
Centaurea adpressa
Centaurea aegyptiaca
Centaurea aeolica
Centaurea aggregata
Centaurea akamantis – Akamas centaurea
Centaurea alba
Centaurea albonitens Turrill
Centaurea alpestris
Centaurea alpina
Centaurea ambigua
Centaurea amblyolepis
Centaurea americana – American basketflower, American starthistle
Centaurea ammocyanus
Centaurea antennata Dufour
Centaurea antiochia Boiss.
Centaurea aplolepa
Centaurea aplolepa subsp. carueliana
Centaurea appendicigera C.Koch
Centaurea argentea
Centaurea ascalonica
Centaurea aspera L. – rough starthistle
Centaurea atacamensis (Reiche) I.M.Johnst.
Centaurea atropurpurea
Centaurea ×aurata
Centaurea babylonica L.
Centaurea balsamita
Centaurea behen L. – ak behmen (Turkish)
Centaurea bella
Centaurea benedicta – Cnicus
Centaurea bieberseinii
Centaurea borjae
Centaurea bovina
Centaurea bracteata
Centaurea brevifimbriata Hub.-Mor.
Centaurea bulbosa
Centaurea busambarensis Guss.
Centaurea cachinalensis
Centaurea calcitrapa – purple starthistle, red starthistle, "caltrop"
Centaurea calcitrapoides
Centaurea cariensis Boiss.
Centaurea cariensiformis Hub.-Mor.
Centaurea caroli-henrici Gabrieljan & Dittrich
Centaurea centaurium L.
Centaurea chilensis
Centaurea cineraria – velvet centaurea, dusty miller
Centaurea clementei
Centaurea collina L.
Centaurea corymbosa
Centaurea crithmifolia
Centaurea crocodylium
Centaurea cyanoides J.Berggr. & Wahlenb.
Centaurea cyanus – cornflower, bachelor's button, boutonniere flower, hurtsickle, bluebottle, basketflower
Centaurea damascena
Centaurea debeauxii Gren. & Godr.
Centaurea demirizii Wagenitz
Centaurea depressa – low cornflower
Centaurea deusta
Centaurea diffusa – diffuse knapweed, white knapweed, tumble knapweed
Centaurea diluta – North African knapweed
Centaurea drabifolia Sm.
Centaurea drabifolioides Hub.-Mor.
Centaurea dschungarica
Centaurea emilae Hüseynova et Qaraxani[13]
Centaurea eriophora
Centaurea eryngioides
Centaurea filiformis
Centaurea fischeri Willd.
Centaurea floccosa
Centaurea foliosa Boiss. & Kotschy
Centaurea forojuliensis
Centaurea friderici Vis. – palagruška zečina (Croatian)
Centaurea gayana
Centaurea glaberrima Tausch
Centaurea glastifolia
Centaurea grinensis
Centaurea gymnocarpa
Centaurea haradjianii Wagenitz
Centaurea hedgei
Centaurea helenioides Boiss.
Centaurea hermannii F.Hermann
Centaurea horrida Badarò – fiordaliso spinoso (Italian)
Centaurea hyalolepis
Centaurea hypoleuca
Centaurea iberica – Iberian starthistle, Iberian knapweed
Centaurea idaea – katsoula, tsita (Cretan Greek)
Centaurea imperialis Hausskn. ex Bornm.
Centaurea jabukensis
Centaurea jacea – brown knapweed, brownray knapweed
Centaurea kasakorum
Centaurea kopetaghensis
Centaurea kotschyana Heuff.
Centaurea lanulata
Centaurea leptophylla
Centaurea leucophylla
Centaurea limbata
Centaurea lydia Boiss.
Centaurea macrocephala Puschk. ex Willd. – globe knapweed, Armenian basketflower
Centaurea maculosa – spotted knapweed (might belong in C. stoebe subsp. micranthos)
Centaurea mannagettae
Centaurea margaritalba Klok.
Centaurea marschalliana
Centaurea melitensis – Maltese starthistle; tocalote, tocolote (California)
Centaurea minor
Centaurea moschata – sweet sultan
Centaurea ×moncktonii C.E.Britton – meadow knapweed, protean knapweed (= C. ×pratensis Thuill non Salisb.)
Centaurea monocephala
Centaurea montana – montane knapweed, perennial cornflower, mountain cornflower, mountain bluet
Centaurea napifolia L. – fiordaliso romano (Italian)
Centaurea nervosa Rchb. ex Steud.
Centaurea nigra – common knapweed, black knapweed, lesser knapweed, hardheads
Centaurea nigrescens – Tyrol knapweed, short-fringed knapweed, Tyrol thistle
Centaurea nigrifimbria (C.Koch) Sosn.
Centaurea nivea (Bornm.) Wagenitz
Centaurea onopordifolia
Centaurea orientalis L.
Centaurea ornata Willd.
Centaurea ovina
Centaurea pallescens Delile
Centaurea paniculata L.
Centaurea parlatoris
Centaurea pecho
Centaurea phrygia – wig knapweed
Centaurea pindicola
Centaurea polypodiifolia
Centaurea ×pratensis Salisb. (C. jacea × C. nigra) – meadow knapweed
Centaurea procurrens
Centaurea ×psammogena G.Gayer. (C. diffusa × C. stoebe subsp. micranthos)
Centaurea pseudocaerulescens
Centaurea pseudophrygia C.A.Mey.
Centaurea pulcherrima Willd.
Centaurea pullata L.
Centaurea pumilio
Centaurea ragusina L.
Centaurea rigida
Centaurea rothrockii Greenm. – Mexican basketflower, Rothrock's basketflower, Rothrock's knapweed
Centaurea ruthenica
Centaurea rutifolia Sm.
Centaurea sadleriana – Pannonian knapweed
Centaurea salicifolia Bieb. ex Willd.
Centaurea scabiosa – greater knapweed
Centaurea scannensis
Centaurea scoparia
Centaurea scopulorum Boiss. & Heldr.
Centaurea seguenzae
Centaurea seridis L.
Centaurea sibirica
Centaurea simplicicaulis
Centaurea sinaica
Centaurea solstitialis – yellow starthistle, golden starthistle, yellow cockspur, St. Barnaby's thistle, Barnaby thistle
Centaurea speciosa
Centaurea sphaerocephala L.
Centaurea stenolepis
Centaurea stoebe L.
Centaurea stoebe subsp. micranthos (Gugler) Hayek
Centaurea straminicephala
Centaurea sulphurea – Sicilian starthistle
Centaurea tauromenitana Guss.
Centaurea tenoreana
Centaurea tommasinii
Centaurea transalpina Schleich. ex DC.
Centaurea tchihatcheffii — yanardöner (Turkish)
Centaurea trichocephala Bieb. ex Willd. – featherhead knapweed
Centaurea triniifolia
Centaurea triumfettii All.
Centaurea ucriae Lacaita
Centaurea uniflora Turra
Centaurea verbascifolia Vahl
Centaurea verutum L.
Centaurea virgata
Centaurea virgata subsp. squarrosa – squarrose knapweed
Centaurea wiedemanniana Fisch. & Mey.
Centaurea yozgatensis Wagenitz
Formerly placed here
Plant species placed in Centaurea in former times include:
Acroptilon repens – Russian knapweed (as C. repens)
Cheirolophus crassifolius – Maltese rock-centaury (as C. crassifolia, C. spathulata)
Femeniasia balearica (as C. balearica)
Volutaria muricata (as C. muricata)
Centaurea is a genus of over 700 species of herbaceous thistle-like flowering plants in the family Asteraceae. Members of the genus are found only north of the equator, mostly in the Eastern Hemisphere; the Middle East and surrounding regions are particularly species-rich. In the western United States, yellow starthistles are an invasive species. Around the year 1850, seeds from the plant had arrived to the state of California. It is believed that those seeds came from South America.
Common names
Common names for this genus are centaury, centory, starthistles, knapweeds, centaureas and the more ambiguous "bluets"; a vernacular name used for these plants in parts of England is "loggerheads" (common knapweed). The Plectocephalus group – possibly a distinct genus – is known as basketflowers. "Cornflower" is used for a few species, but that term more often specifically means either C. cyanus (the annual cornflower) or Centaurea montana (the perennial cornflower). The common name "centaury" is sometimes used, although this also refers to the unrelated plant genus Centaurium.
The name is said to be in reference to Chiron, the centaur of Greek mythology who discovered medicinal uses of a plant eventually called "centaury".
Description
Knapweeds are robust weedy plants. Their leaves, spiny in some species, are usually deeply divided into elongated lobes at least in the plants' lower part, becoming entire towards the top. The "flowers" (actually pseudanthium inflorescences) are diverse in colour, ranging from intense blues, reds and yellows to any mixture of these and lighter shades towards white. Often, the disk flowers are much darker or lighter than the ray flowers, which also differ in morphology and are sterile. Each pseudanthium sits atop a cup- or basket-like cluster of scaly bracts, hence the name "basketflowers". Many species, in particular those inhabiting more arid regions, have a long and strong taproot.
Certain knapweeds have a tendency to dominate large stretches of landscape together with a few other plants, typically one or two grasses and as many other large herbaceous plants. The common knapweed (C. nigra) for example is plentiful in the mesotrophic grasslands of England and nearby regions. It is most prominently found in pastures or meadows dominated by cock's-foot (Dactylis glomerata) as well as either of crested dog's-tail (Cynosurus cristatus) and false oat-grass (Arrhenatherum elatius). It is also often found in mesotrophic grassland on rendzinas and similar calcareous soils in association with glaucous sedge (Carex flacca), sheep's fescue (Festuca ovina), and either tor-grass (Brachypodium pinnatum) and rough hawkbit (Leontodon hispidus), or upright brome (Bromus erectus). In these grasslands, greater knapweed (C. scabiosa) is found much more rarely by comparison, often in association with red fescue (Festuca rubra) in addition to cock's-foot and false oat-grass.
Due to their habit of dominating ecosystems under good conditions, many Centaurea species can become invasive weeds in regions where they are not native. In parts of North America, diffuse knapweed (C. diffusa), spotted knapweed (C. maculosa) and yellow starthistle (C. solstitialis) cause severe problems in agriculture due to their uncontrolled spread. The seeds are typically transported by human traffic, in particular the tires of all-terrain vehicles. The two knapweeds are harmful mainly because they are strongly allelopathic, producing powerful toxins in their roots that stunt the growth of plants around them not adapted to this. Yellow starthistle, meanwhile, is inedible to most livestock due to its spines and apparently outright poisonous to horses and other equines. However, efficient methods of biological control by insect pests of these weeds have been developed; the knapweeds can also exploited to their detriment by targeted grazing. Controlled burning may also be used, though the timing is important to avoid the plants having seeded already, and neither allowing sufficient time for them to regrow from the rootstock.
Yet other species of Centaurea – mostly ones that occur between Italy and the Caucasus – are endemics of a single island or valley, and some of these are endangered. The Akamas Centaurea (Centaurea akamantis) of Cyprus is almost extinct, while the western Caucasus endemics C. leptophylla and C. straminicephala are at least very rare and C. hedgei and C. pecho from the same region are certainly not abundant either. The last four species would be adversely affected by the proposed Yusufeli Dam, which might actually destroy enough habitat to push the two rarer ones over the brink of extinction.
Centaurea are copious nectar producers, especially on high-lime soils. The high nectar yield of the genus makes it very attractive to insects such as butterflies – including the endangered Karner blue (Plebejus melissa samuelis) which visits introduced spotted knapweed – and day-flying moths – typically Zygaenidae, such as Zygaena loti or the six-spot burnet (Z. filipendulae). The larvae of some other Lepidoptera species use Centaurea species as food plants; see List of Lepidoptera that feed on Centaurea. Several of these are used in biological control of invasive knapweeds and starthistles.
Larvae of several true weevils (Curculionidae) of the subfamily Lixinae also feed on Centaurea. Some genera – such as Larinus whose larval food is flowerheads – have many species especially adapted to particular knapweeds or starthistle and are used in biological control too. These include the yellow starthistle flower weevil (L. curtus) for yellow starthistle, lesser knapweed flower weevil (L. minutus) for diffuse knapweed and blunt knapweed flower weevil (L. obtusus) for spotted knapweed. Broad-nosed seedhead weevil (Bangasternus fausti) larvae eat diffuse, spotted and squarrose knapweed (C. virgata ssp. squarrosa), while those of the yellow starthistle bud weevil (B. orientalis) do not seem to live on anything other than yellow starthistle and occasionally purple starthistle (C. calcitrapa). But perhaps most efficient in destroying developing yellow starthistle seedheads is the larva of the yellow starthistle hairy weevil (Eustenopus villosus). Knapweed root weevil (Cyphocleonus achates) larvae bore into the roots of spotted and to a lesser extentely diffuse knapweed, sometimes killing off the entire plant.
Also used in biological control are Tephritidae (peacock flies) whose larvae feed on Centaurea. Knapweed peacock fly (Chaetorellia acrolophi) larvae eat spotted knapweed and some other species. The yellow starthistle peacock fly (C. australis) has an initial generation each year which often uses cornflower (C. cyanus) as larval food; later generations switch to yellow starthistle. The flies are generally considered less efficient in destroying the growing seedheads than the weevils, but may be superior under certain conditions; employing flies and weevils in combination is expensive and does not noticeably increase their effect.
Use by humans
Although the genus may be considered by a quite significant number of relatively informed individuals to have an overall negative impact on human interests, particularly agricultural interests, the situation is not straightforward enough to simply declare the genus, or, at least, its most aggressively-spreading species, altogether negative. For instance, due to their moderate to high nectar production, which can occur over a comparatively long duration, many species of Centaurea are popular food sources for insects that may otherwise attack certain crops.[citation needed] It may be advisable for some types of farms to allow certain species in this genus, such as cornflower (C. cyanus) in a European setting, to grow adjacent to fields. Although they support and attract many types of beneficial life (not just beetles), these areas are known as beetle banks. When they are present, some pests may be drawn away from crops to them and predatory insects and arachnids that feed upon pest insects will be better-supported by these more naturalized areas. They additionally have the beneficial aspect of supporting pollinators, unlike many field crops such as maize. Moreover, being untreated with pesticides and providing more diversity, plants growing in more wild areas adjacent to farms produce more insects that attract and support birds which can also feed on pests that would harm crops. Insect production is especially high for beetle banks that have enough plants that serve in the role of host plant for immature insects, rather than just in the roles of adult food and/or shelter provision.
Some plants which are considered invasive or problematic in certain areas can have beneficial qualities that outweigh their negative qualities from a human and/or human agricultural point of view, although this sometimes requires some human management – particularly if adequate biological control has not been established for the more aggressive species. An example is wild parsnip, Pastinaca sativa, which produces florets that feed predatory (and other beneficial) insects as well as large tubular stems that provide winter shelter for native bees, wasps, and other organisms that can be beneficial for agriculture. The plant is considered invasive in some areas of the United States and is also often considered undesirable due to its ability to cause contact skin irritation. However, it also serves as a host plant for the black swallowtail butterfly, helps to bring nutrients up from soils with its deep taproot, and possesses evergreen foliage even in climate zones such as US zone 6. This foliage increases soil warmth and moisture which can be beneficial for certain types of life. Perhaps the most dramatic example of a generally disliked plant's beneficial qualities being usually overlooked is the often-despised ragwort, Jacobaea vulgaris, which topped the list by a large amount for nectar production in a UK study, with a production per floral unit of (2921 ± 448μg). This very high nectar production, coupled with its early blooming period, makes the plant helpful for the establishment of bee colonies in spring — a period that is often not well-served by commercial flower meadow seed mixes. It also has the situationally-beneficial quality of being a spring ephemeral, as well as an annual that lacks difficult-to-combat roots. Plants that provide necessary structural supports for invertebrate and small vertebrate predators can help to keep overall pest populations low.
The abundant nectar produced by C. solstitialis flowers attracts many pollinators. This is another reason for the success of the (situationally) highly invasive species. Due to genetic differences related to evolutionary adaption, not all members of Centaurea produce the same amount of nectar. Growing conditions, such as climate and soil, can have a very strong impact, even if the plants grow and flower. For instance, cornflower plants, Centaurea cyanus, produced 33% less seasonal nectar than Centaurea nigra in a UK study. C. nigra also ranked higher than ragwort in another UK study, although ragwort was still in the top 10 for yearly nectar production. The strong nectar production of certain members of the genus can be exploited to the farmer's advantage, possibly in combination with biological control. In particular, the yellow starthistle (C. solstitialis) as well as spotted knapweed (C. maculosa) are major honey plants for beekeepers. Monofloral honey from these plants is light and slightly tangy, and one of the finest honeys produced in the United States – due to its better availability, it is even fraudulently relabeled and sold as the scarce and expensive sourwood honey of the Appalachian Mountains. Placing beehives near stands of Centaurea will cause increased pollination. As most seedheads fail however when biocontrol pests have established themselves, the plants will bloom ever more abundantly in an attempt to replace the destroyed seedheads, to the point where they exhaust their resources in providing food for the pests (seeds), bees (pollen) and humans (honey). Output of allelopathic compounds is also liable to be reduced under such conditions – the plant has to compromise between allocating energy to reproduction and defense. This renders the weeds more likely to be suppressed by native vegetation or crops in the following years, especially if properly timed controlled burning[5] and/or targeted grazing by suitable livestock are also employed. While yellow starthistle and perhaps other species are toxic to equines, some other livestock may eat the non-spiny knapweeds with relish. In Europe, common knapweed (C. nigra) and globe knapweed (C. macrocephala) are locally important pollen sources for honeybees in mid-late summer.
8-Hydroxyquinoline has been identified as a main allelopathic compound produced by diffuse knapweed (C. diffusa); native North American plants are typically sensitive to it, while those of Eastern Europe and Asia Minor usually have coevolved with the knapweed and are little harmed if at all, aided by native microorganisms that break down or even feed on the abundantly secreted compound. Thus, 8-hydroxyquinoline is potentially useful to control American plants that have become invasive weeds in the diffuse knapweed's native range.
Arctiin, found in C. imperialis, has shown anticancer activity in laboratory studies. The roots of the long-lost C. foliosa, an endemic of Hatay Province (Turkey), are used in folk medicine, and other species are presumably too. A South Italian variety[verification needed] of the purple starthistle (C. calcitrapa) is traditionally consumed by ethnic Albanians (Arbëreshë people) in the Vulture area (southern Italy); e.g. in the Arbëreshë communities in Lucania the young whorls of C. calcitrapa are boiled and fried in mixtures with other weedy non-cultivated greens. According to research by the Michael Heinrich group at the Centre for Pharmacognosy and Phytotherapy (School of Pharmacy, University of London) "the antioxidant activity [...] of the young whorls of Centaurea calcitrapa, both in the DPPH and in the lipid peroxidation inhibition assays, [is] very interesting and [the] species should be investigated phytochemically and biochemically focusing on these properties". Extracts from C. calcitrapa were furthermore found to have significant xanthine oxidase (XO)-inhibiting activity.
Spotted knapweed as well as other species are rich in cnicin, a bitter compound found mainly in the leaves and often used to flavor the digestif amaro. In western Crete, Greece a local variety[verification needed] of C. calcitrapa called gourounaki (γουρουνάκι "little pig") also has its leaves eaten boiled by the locals. In the same island an endemic local species, C. idaea called katsoula (κατσούλα), tsita (τσίτα) or aspragatha (ασπραγκάθα), has its leaves eaten boiled by the locals too.
Some species are cultivated as ornamental plants in gardens. As regards other aspects of popular culture, cornflower (C. cyanus) is the floral emblem of Östergötland province (Sweden) – where is it called blåklint, literally "blue mountain" – and of Päijänne Tavastia region in Finland, where it is known as ruiskaunokki ("rye-beaks") or ruiskukka ("rye-flower"). It is also the national flower of Estonia where its local name rukkilill means "rye-lily", Belarus where it is called vałoška (Belarusian: валошка), and one of those of Germany where it is called Kornblume ("cornflower"). The origin of the name "caltrop" for the ancient low-tech area denial weapon is probably in some way connected with C. calcitrapa and its spiny seeds. This plant is attested to by the colloquial name "caltrop" at a time when the weapons were still called by their Roman name tribulus. Lastly, the color cornflower blue is named after C. cyanus. Cornflower is also used as a cut flower.
As namesake member of the subtribe Centaureinae of tribe Cardueae, the knapweeds are probably most closely related to genera such as Carthamus (distaff thistles), Cnicus (blessed thistle), Crupina (crupinas) or Notobasis (Syrian thistle), and somewhat less closely to most other thistles. The monotypic Cnicus seems in fact to properly belong in Centaurea.
Research in the late 20th century shows that Centaurea as traditionally defined is polyphyletic. A number of 19th- and 20th-century efforts to reorganize the genus were not successful, and it is not yet clear what the consequences of the recent research will be for classification of this genus and other related genera. The type species C. centaurium stands somewhat apart from the main lineage of knapweeds and thus the taxonomic consequences of a rearrangement might be severe, with hundreds of species needing to be moved to new genera. It has thus been proposed to change the type species to one of the main lineages to avoid this problem. What seems certain however is that the basketflowers – presently treated as a section Plectocephalus – will be reinstated as a distinct genus in the near future. The rock-centauries (Cheirolophus), formerly usually included in Centaurea, are now already treated as separate genus.
Better-known Centaurea species include:
Centaurea acaulis
Centaurea adpressa
Centaurea aegyptiaca
Centaurea aeolica
Centaurea aggregata
Centaurea akamantis – Akamas centaurea
Centaurea alba
Centaurea albonitens Turrill
Centaurea alpestris
Centaurea alpina
Centaurea ambigua
Centaurea amblyolepis
Centaurea americana – American basketflower, American starthistle
Centaurea ammocyanus
Centaurea antennata Dufour
Centaurea antiochia Boiss.
Centaurea aplolepa
Centaurea aplolepa subsp. carueliana
Centaurea appendicigera C.Koch
Centaurea argentea
Centaurea ascalonica
Centaurea aspera L. – rough starthistle
Centaurea atacamensis (Reiche) I.M.Johnst.
Centaurea atropurpurea
Centaurea ×aurata
Centaurea babylonica L.
Centaurea balsamita
Centaurea behen L. – ak behmen (Turkish)
Centaurea bella
Centaurea benedicta – Cnicus
Centaurea bieberseinii
Centaurea borjae
Centaurea bovina
Centaurea bracteata
Centaurea brevifimbriata Hub.-Mor.
Centaurea bulbosa
Centaurea busambarensis Guss.
Centaurea cachinalensis
Centaurea calcitrapa – purple starthistle, red starthistle, "caltrop"
Centaurea calcitrapoides
Centaurea cariensis Boiss.
Centaurea cariensiformis Hub.-Mor.
Centaurea caroli-henrici Gabrieljan & Dittrich
Centaurea centaurium L.
Centaurea chilensis
Centaurea cineraria – velvet centaurea, dusty miller
Centaurea clementei
Centaurea collina L.
Centaurea corymbosa
Centaurea crithmifolia
Centaurea crocodylium
Centaurea cyanoides J.Berggr. & Wahlenb.
Centaurea cyanus – cornflower, bachelor's button, boutonniere flower, hurtsickle, bluebottle, basketflower
Centaurea damascena
Centaurea debeauxii Gren. & Godr.
Centaurea demirizii Wagenitz
Centaurea depressa – low cornflower
Centaurea deusta
Centaurea diffusa – diffuse knapweed, white knapweed, tumble knapweed
Centaurea diluta – North African knapweed
Centaurea drabifolia Sm.
Centaurea drabifolioides Hub.-Mor.
Centaurea dschungarica
Centaurea emilae Hüseynova et Qaraxani[13]
Centaurea eriophora
Centaurea eryngioides
Centaurea filiformis
Centaurea fischeri Willd.
Centaurea floccosa
Centaurea foliosa Boiss. & Kotschy
Centaurea forojuliensis
Centaurea friderici Vis. – palagruška zečina (Croatian)
Centaurea gayana
Centaurea glaberrima Tausch
Centaurea glastifolia
Centaurea grinensis
Centaurea gymnocarpa
Centaurea haradjianii Wagenitz
Centaurea hedgei
Centaurea helenioides Boiss.
Centaurea hermannii F.Hermann
Centaurea horrida Badarò – fiordaliso spinoso (Italian)
Centaurea hyalolepis
Centaurea hypoleuca
Centaurea iberica – Iberian starthistle, Iberian knapweed
Centaurea idaea – katsoula, tsita (Cretan Greek)
Centaurea imperialis Hausskn. ex Bornm.
Centaurea jabukensis
Centaurea jacea – brown knapweed, brownray knapweed
Centaurea kasakorum
Centaurea kopetaghensis
Centaurea kotschyana Heuff.
Centaurea lanulata
Centaurea leptophylla
Centaurea leucophylla
Centaurea limbata
Centaurea lydia Boiss.
Centaurea macrocephala Puschk. ex Willd. – globe knapweed, Armenian basketflower
Centaurea maculosa – spotted knapweed (might belong in C. stoebe subsp. micranthos)
Centaurea mannagettae
Centaurea margaritalba Klok.
Centaurea marschalliana
Centaurea melitensis – Maltese starthistle; tocalote, tocolote (California)
Centaurea minor
Centaurea moschata – sweet sultan
Centaurea ×moncktonii C.E.Britton – meadow knapweed, protean knapweed (= C. ×pratensis Thuill non Salisb.)
Centaurea monocephala
Centaurea montana – montane knapweed, perennial cornflower, mountain cornflower, mountain bluet
Centaurea napifolia L. – fiordaliso romano (Italian)
Centaurea nervosa Rchb. ex Steud.
Centaurea nigra – common knapweed, black knapweed, lesser knapweed, hardheads
Centaurea nigrescens – Tyrol knapweed, short-fringed knapweed, Tyrol thistle
Centaurea nigrifimbria (C.Koch) Sosn.
Centaurea nivea (Bornm.) Wagenitz
Centaurea onopordifolia
Centaurea orientalis L.
Centaurea ornata Willd.
Centaurea ovina
Centaurea pallescens Delile
Centaurea paniculata L.
Centaurea parlatoris
Centaurea pecho
Centaurea phrygia – wig knapweed
Centaurea pindicola
Centaurea polypodiifolia
Centaurea ×pratensis Salisb. (C. jacea × C. nigra) – meadow knapweed
Centaurea procurrens
Centaurea ×psammogena G.Gayer. (C. diffusa × C. stoebe subsp. micranthos)
Centaurea pseudocaerulescens
Centaurea pseudophrygia C.A.Mey.
Centaurea pulcherrima Willd.
Centaurea pullata L.
Centaurea pumilio
Centaurea ragusina L.
Centaurea rigida
Centaurea rothrockii Greenm. – Mexican basketflower, Rothrock's basketflower, Rothrock's knapweed
Centaurea ruthenica
Centaurea rutifolia Sm.
Centaurea sadleriana – Pannonian knapweed
Centaurea salicifolia Bieb. ex Willd.
Centaurea scabiosa – greater knapweed
Centaurea scannensis
Centaurea scoparia
Centaurea scopulorum Boiss. & Heldr.
Centaurea seguenzae
Centaurea seridis L.
Centaurea sibirica
Centaurea simplicicaulis
Centaurea sinaica
Centaurea solstitialis – yellow starthistle, golden starthistle, yellow cockspur, St. Barnaby's thistle, Barnaby thistle
Centaurea speciosa
Centaurea sphaerocephala L.
Centaurea stenolepis
Centaurea stoebe L.
Centaurea stoebe subsp. micranthos (Gugler) Hayek
Centaurea straminicephala
Centaurea sulphurea – Sicilian starthistle
Centaurea tauromenitana Guss.
Centaurea tenoreana
Centaurea tommasinii
Centaurea transalpina Schleich. ex DC.
Centaurea tchihatcheffii — yanardöner (Turkish)
Centaurea trichocephala Bieb. ex Willd. – featherhead knapweed
Centaurea triniifolia
Centaurea triumfettii All.
Centaurea ucriae Lacaita
Centaurea uniflora Turra
Centaurea verbascifolia Vahl
Centaurea verutum L.
Centaurea virgata
Centaurea virgata subsp. squarrosa – squarrose knapweed
Centaurea wiedemanniana Fisch. & Mey.
Centaurea yozgatensis Wagenitz
Formerly placed here
Plant species placed in Centaurea in former times include:
Acroptilon repens – Russian knapweed (as C. repens)
Cheirolophus crassifolius – Maltese rock-centaury (as C. crassifolia, C. spathulata)
Femeniasia balearica (as C. balearica)
Volutaria muricata (as C. muricata)