Gymnosperm Leaves: Conjoint Vascular Bundles in Single Needled Pinus
cross section: Pinus needle
magnification: 100x
Triarch quadruple stain
Berkshire Community College Bioscience Image Library
Deep to the hypodermis lies an undifferentiated photosynthetic mesophyll. Cells are distinctively lobed with infolded cell walls. They are filled with chloroplasts and starch grains that may be difficult to see because of an accumulation of dark staining tannins and resins. A few resin canals can be seen close to the hypodermal side of the mesophyll.
A central vascular bundle is wrapped in a single layered endodermis with a well-defined casparian strip whose end walls may become heavily suberized with age.
Deep to the endodermis lies a multilayered parenchymous pericycle with two vascular bundles separated by an often indistinct band of sclerenchymal cells. The pericycle also contains transfusion tissues of protein rich albuminous cells which abut and assist the phloem in the transport nutrients and elongated tracheidal cells which abut and assists the xylem in the transport of water.
Most species possess two conjoint, collateral vascular bundles, surrounded and supported by the tissues of the pericycle. Xylem tracheids lie towards the adaxial surface and phloem sieve tubes towards abaxial surface of the leaf. Xylem vessels and fibers, and phloem companion cells are absent in Gymnosperms.
While vascular bundles are closed some cambium may persist near the base of the needle.
Visit the BCC Bioscience Image featuring the Microscopic World of Plants. www.berkshirecc.edu/biologyimages
Technical Questions:bioimagesoer@gmail.com
Gymnosperm Leaves: Conjoint Vascular Bundles in Single Needled Pinus
cross section: Pinus needle
magnification: 100x
Triarch quadruple stain
Berkshire Community College Bioscience Image Library
Deep to the hypodermis lies an undifferentiated photosynthetic mesophyll. Cells are distinctively lobed with infolded cell walls. They are filled with chloroplasts and starch grains that may be difficult to see because of an accumulation of dark staining tannins and resins. A few resin canals can be seen close to the hypodermal side of the mesophyll.
A central vascular bundle is wrapped in a single layered endodermis with a well-defined casparian strip whose end walls may become heavily suberized with age.
Deep to the endodermis lies a multilayered parenchymous pericycle with two vascular bundles separated by an often indistinct band of sclerenchymal cells. The pericycle also contains transfusion tissues of protein rich albuminous cells which abut and assist the phloem in the transport nutrients and elongated tracheidal cells which abut and assists the xylem in the transport of water.
Most species possess two conjoint, collateral vascular bundles, surrounded and supported by the tissues of the pericycle. Xylem tracheids lie towards the adaxial surface and phloem sieve tubes towards abaxial surface of the leaf. Xylem vessels and fibers, and phloem companion cells are absent in Gymnosperms.
While vascular bundles are closed some cambium may persist near the base of the needle.
Visit the BCC Bioscience Image featuring the Microscopic World of Plants. www.berkshirecc.edu/biologyimages
Technical Questions:bioimagesoer@gmail.com