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Related to pith ray: wood ray
pith ray[′pith ‚rā]
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
medullary ray, pith ray
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.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.