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.

Short, thickened, mostly underground stem that constitutes the resting stage of certain seed plants. It is often an organ of food storage, reproduction, or both. It bears minute scale leaves, each with a bud that has the potential for developing into a new plant. The common potato is a typical tuber; the much-reduced leaves and associated buds form its “eyes.” The term is also used imprecisely but widely for fleshy roots or rhizomes that resemble tubers (e.g., the “tuber” of the dahlia, actually a tuberous root).

Learn more about tuber with a free trial on Britannica.com.