The word rhizome comes from two terms: rhizo- means root and the suffix -oma which means bulge. The rhizome is in fact a swollen modification of the stem that performs particular reserve functions. The rhizome is an underground organ with a generally horizontal geomorphism. The rhizome is an organ particularly present in many ferns and aquatic plants (such as water lilies). In other species, as in Iris, the rhizome is rich in parenchymal tissues, with a reserve function, which contain starch. In higher plants (as in Angiosperms) it also plays a reproductive function; this is indeed equipped with gems that allow the development of a new individual.
The ability of this organ of the plant to give life to new individuals, with the same genetic characteristics, is exploited in nursery techniques, especially for the reproduction of flowering plants; in fact this organ has the ability to generate cells differentiated superiorly in buds polloniferous and inferior primordial radicals. From the morphological point of view this organ can have an elongated, ramified conformation, decurrent under the surface of the ground, or, in other cases, short and cylindrical, arranged in a more or less vertical position. The fundamental function of the rhizome is to allow the plant unfavorable climatic conditions regenerating, at the end of these, new plants. The rhizome is a characteristic organ of some herbaceous species and should not be confused with the stolone, which is instead the part of the stem of some plants that, crawling on the ground, performs vegetative reproduction functions.