In botany, a rhizome is a horizontal stem of a plant that is usually found underground, often sending out roots and shoots from its nodes. Plants with underground rhizomes include ginger, hops, and turmeric, significant for their medicinal properties, and the weeds Johnson grass, bermuda grass, and purple nut sedge. Some plants have rhizomes that grow above ground or that sit at the soil surface, including some Iris species, and ferns, whose spreading stems are rhizomes. Rhizomes may also be referred to as creeping rootstalks, or rootstocks. A stolon is similar to a rhizome, but, unlike a rhizome, which is the main stem of the plant, a stolon sprouts from an existing stem, has long internodes, and generates new shoots at the end, e.g., the strawberry plant. In general, rhizomes have short internodes; they send out roots from the bottom of the nodes and new upward-growing shoots from the top of the nodes.
For many plants, the rhizome is used by gardeners to propagate the plants by a process known as vegetative reproduction. Examples of plants that are propagated this way include asparagus, ginger, irises, Lily of the Valley, Cannas, and sympodial orchids.
A stem tuber is a thickened part of a rhizome or stolon that has been enlarged for use as a storage organ.  In general, a tuber is high in starch, for example, the common potato, which is a modified stolon. The term tuber is often used imprecisely, and is sometimes applied to plants with rhizomes.
- Kingsley R. Stern Introductory Plant Biology, 10th ed. ISBN 0072909412