Medullary Ray

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medullary ray

[me′dəl·ə·rē ‚rā]
An extension of pith between vascular bundles in the plant stem. Also known as pith ray.

Medullary Ray


a single or polystichous layer of parenchymal cells that intersect the lignin and bast of stems and roots of dicotyledonous plants. Medullary rays serve a storage function and transport matter in a horizontal direction.

medullary ray, pith ray

medullary rays
In a cross section of a tree or log, one of the ribbons of tissue extending radially from the pith; may vary from microscopic to 4 in. (10 cm) or more in oak; used to store and transport food horizontally within the tree.