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Tree biology

Contents: - periderm - phellem - cork cambium - phelloderm - cortex - phloem- phloem rays - sieve tube element - companion cells - cambial zone (cambium) - bark - xylem - growth ring - vessels - tyloses - parenchyma - axial parenchyma - multiserrate ray parenchyma - uniserrate ray parenchyma - fibers - symplast - apoplast - growth ring/ray compartment -wounding response - decay development

Select any of the above terms to view its location in the tree cross section. Text at bottom.


Phellem in the very outer portion of the outer bark. It often flakes off in plates or peels and is shed from the tree. Fissures and cracks form in phellem exposing the phellogen in many species. Chlorophyll (green in the illustration above) can often been seen near the phellogen in fissures.