Herbaceous Dicot Stem: Pelargonium
Cross section: Pelargonium
Common name: Storksbill Geranium
Magnification: 40x
Berkshire Community College Bioscience Image Library
Unlike most herbaceous dicots, Pelargonium is capable of secondary growth in dermal and vascular tissues.
The young stem is wrapped in a single layer of epidermis that is quickly replaced by a protective secondary zone of cork rich periderm. The outermost layer of periderm consists 4 to 6 layers of cork cells, the phellem. Deep to this are 1 to 2 layers of cork cambium or phellogen and just beneath that a single layer of phelloderm.
A cortex of parenchyma cells is separated from the stele by a well defined starch sheath. Immediately interior to the starch sheath is a heavy ring of red staining sclerenchymal perivascular fibers that encircles and supports the underlying vascular tissues. Deep to this layer is a band of phloem and deep to this a zone of xylem. While Pelargonium produces a small amount of secondary phloem and xylem it may be difficult to differentiate from the primary vascular tissues.
The center of the stem is occupied by a pith of parenchyma cells that contain numerous starch storing amyloplasts.
Technical Questions:bioimagesoer@gmail.com
Herbaceous Dicot Stem: Pelargonium
Cross section: Pelargonium
Common name: Storksbill Geranium
Magnification: 40x
Berkshire Community College Bioscience Image Library
Unlike most herbaceous dicots, Pelargonium is capable of secondary growth in dermal and vascular tissues.
The young stem is wrapped in a single layer of epidermis that is quickly replaced by a protective secondary zone of cork rich periderm. The outermost layer of periderm consists 4 to 6 layers of cork cells, the phellem. Deep to this are 1 to 2 layers of cork cambium or phellogen and just beneath that a single layer of phelloderm.
A cortex of parenchyma cells is separated from the stele by a well defined starch sheath. Immediately interior to the starch sheath is a heavy ring of red staining sclerenchymal perivascular fibers that encircles and supports the underlying vascular tissues. Deep to this layer is a band of phloem and deep to this a zone of xylem. While Pelargonium produces a small amount of secondary phloem and xylem it may be difficult to differentiate from the primary vascular tissues.
The center of the stem is occupied by a pith of parenchyma cells that contain numerous starch storing amyloplasts.
Technical Questions:bioimagesoer@gmail.com