tuber, enlarged tip of a rhizome (underground stem) that stores food. Although much modified in structure, the tuber contains all the usual stem parts—bark, wood, pith, nodes, and internodes. The eyes of a potato tuber are nodes where sprouts appear, and they are arranged in the same spiral pattern characteristic of buds on an aerial stem.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.