In addition, tiny new corms, called cormels or cormlets, may form at the base of the secondary corms, piling on top of one another, sometimes in large quantities. These must grow to full size before they will flower. As a corm uses stored food reserves to form leaves, flowers, and new cormels, its energy is depleted and then it virtually disappears, usually within a season. The next year's growth emerges from one or more of the fully developed offshoot corms. At right angles to the stems are eyes from which new shoots emerge, and obvious roots growing from the bottom of the stem.
Rhizomes reproduce by spreading horizontally underground, or on the ground surface.
As the rhizome matures, older parts often become woody and produce few flowering stalks. Rhizomes are planted just below the surface of the soil, unlike true bulbs or corms, which must be planted deeper for more protection from the elements. The tuber stores the plant's food, and it deteriorates as new tubers form. Plants with tuberous roots, such as dahlias, have enlarged, often elongated, underground roots. The root stores nutrients and, as it matures, produces more shoots above ground, forming large clumps which can be divided.