Rhizome

Underground stem in which various plants asexually reproduce via budding

In botany and dendrology, a rhizome ( RY-zohm) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow horizontally.

From Wikipedia, under CC BY-SA. More on occurri.