A rhizome is the main stem of the plant that runs typically underground and horizontally to the soil surface.[5][6] Rhizomes have nodes and internodes and auxiliary buds.[7] Roots do not have nodes and internodes and have a root cap terminating their ends.[8] In general, rhizomes have short internodes, send out roots from the bottom of the nodes, and generate new upward-growing shoots from the top of the nodes. Astolon is similar to a rhizome, but stolon sprouts from an existing stem having long internodes and generating new shoots at the ends, they are often also called runners such as in thestrawberry plant.[9]
Astem tuber is a thickened part of a rhizome or stolon that has been enlarged for use as astorage organ.[10] In general, a tuber is high instarch, e.g. thepotato, which is a modified stolon. The term "tuber" is often used imprecisely and is sometimes applied to plants with rhizomes.
The plant uses the rhizome to store starches,proteins, and other nutrients. These nutrients become useful for the plant when new shoots must be formed or when the plant dies back for the winter.[4] If a rhizome is separated, each piece may be able to give rise to a new plant. This is a process known asvegetative reproduction and is used by farmers and gardeners to propagate certain plants. This also allows for lateral spread of grasses likebamboo andbunch grasses. Examples of plants that are propagated this way includehops,asparagus,ginger, irises,lily of the valley,cannas, andsympodialorchids.
Stored rhizomes are subject tobacterial andfungal infections, making them unsuitable for replanting and greatly diminishing stocks. However, rhizomes can also be produced artificially fromtissue cultures. The ability to easily grow rhizomes from tissue cultures leads to better stocks for replanting and greater yields.[11] The plant hormonesethylene andjasmonic acid have been found to help induce and regulate the growth of rhizomes, specifically inrhubarb.Ethylene that was applied externally was found to affect internal ethylene levels, allowing easy manipulations of ethylene concentrations.[12] Knowledge of how to use these hormones to induce rhizome growth could help farmers and biologists to produce plants grown from rhizomes, and more easily cultivate and grow better plants.
