corm

corm, vertical, fleshy, underground stem that acts as a food-storage structure in certain seed plants. It bears membranous or scaly leaves and buds, and, unlike in bulbs, these do not appear as visible rings when the corm is cut in half. Corms have a fibrous covering known as a tunic, and the roots emerge from a smooth area at the base known as the basal plate. Corms store starches to fuel growth and to help plants survive unfavourable conditions, and many produce offshoots known as daughter corms or cormels that are used for vegetative reproduction. Typical corms are those of the crocus, gladiolus, and taro. The largest corm is that of the titan arum (Amorphophallus titanum), which can weigh about 70–90 kg (154–200 pounds); the structure provides the energy necessary for the rapid growth of the plant’s enormous inflorescence. Corms are sometimes called solid bulbs, or bulbo-tubers, but they are distinguished from true bulbs and tubers (compare bulb; tuber).