Rhizome

Ginger rhizome

Iris rhizome

In botany, a rhizome is a usually underground, horizontal stem of a plant that often sends out roots and shoots from its nodes. Rhizomes may also be referred to as creeping rootstalks, or rootstocks. A stolon is similar to a rhizome, but exists above ground, sprouting from an existing stem.

Many plants have rhizomes that serve to spread the plant by vegetative reproduction. Examples of plants that do this are asparagus, ginger, irises, Lily of the Valley, Cannas and sympodial orchids. The spreading stems of ferns are also called rhizomes.

A tuber is a thickened part of a stolon that has been enlarged for use as a storage organ. They are typically high in starch. An example of a tuber is the common potato.