Woody Dicot Stem: Epidermis and Cortex in Young Aristolochia Stem Tip
Cross section: Stem Tip in Aristolochia
Magnification: 400x
Berkshire Community College Bioscience Image Library
Unusual activity of lateral meristems results in the fluting or bifurcation of vascular bundles in Aristolochia.
Vascular (fascicular) cambium produce typical vascular bundles with primary xylem of each bundle oriented towards the center of the stem, primary phloem to the outside and fascicular cambium in between.
However, the growing vascular bundles fail to fuse into continuous rings due to unusual activity of the inter vascular cambium. Heavy growth produces large bands of parenchyma cells to the inside and outside of the medullary rays. Rapid expansion of the medullary rays, which extend from pith to cortex, push the vascular bundles further apart, resulting in the characteristic fluting or bifurcation of vascular bundles seen in older stems.
Internal pressures exerted by annual growth of deeper tissues ultimately rupture and tear the cortex, and dermal tissues. The epidermis and cortex in this young stem already show signs of rupture and repair with parenchymal cells.
Technical Questions:bioimagesoer@gmail.com
Woody Dicot Stem: Epidermis and Cortex in Young Aristolochia Stem Tip
Cross section: Stem Tip in Aristolochia
Magnification: 400x
Berkshire Community College Bioscience Image Library
Unusual activity of lateral meristems results in the fluting or bifurcation of vascular bundles in Aristolochia.
Vascular (fascicular) cambium produce typical vascular bundles with primary xylem of each bundle oriented towards the center of the stem, primary phloem to the outside and fascicular cambium in between.
However, the growing vascular bundles fail to fuse into continuous rings due to unusual activity of the inter vascular cambium. Heavy growth produces large bands of parenchyma cells to the inside and outside of the medullary rays. Rapid expansion of the medullary rays, which extend from pith to cortex, push the vascular bundles further apart, resulting in the characteristic fluting or bifurcation of vascular bundles seen in older stems.
Internal pressures exerted by annual growth of deeper tissues ultimately rupture and tear the cortex, and dermal tissues. The epidermis and cortex in this young stem already show signs of rupture and repair with parenchymal cells.
Technical Questions:bioimagesoer@gmail.com