Amorphophallus

This is a large genus of around 245 tropical herbaceous perennials in the arum family (Araceae) that grow from corms. They are native to Asia, Africa and islands of the western Pacific, including Japan and the Philippines. They are generally found in the lowlands of tropical and subtropical areas. The genus name comes from the Geek amorphos, meaning "without form or misshapen, " and phallos, "penis,” referring to the shape of the prominent spadix.

These plants are not frost-tolerant and need to be grown in containers. The corms of some species can survive in the ground to zone 7, but the leaves and flowers do not survive frost. As greenhouse or houseplants, they are heavy feeders and thrive in moist, humus-rich potting mix. In the fall, when the leaf dies down, the corm should be allowed to rest, during which time the corm can be lifted and placed in a dry, warm, pest-free storage (i.e., treated like dahlia tubers). It can be replanted in early spring. If the corm is left in the pot, the potting mix must dry out completely. Watering and feeding should resume only when growth recommences. Plants can be propagated by seeds. Some species produce aerial bulbils on the leaves that fall to the ground and grow. Cormlets (corm offsets) are also produced by most species.

These plants vary in size from small to very large. Most species produce a single, large, compound leaf, which usually appears after the plant has flowered. The flowers consist of a spathe (a modified bract) surrounding a spadix, which is the elongated, unbranched flower stalk. These vary in size and color. Some have a pungent fragrance, but others have a pleasant fragrance. The fruits are berries of various colors. The corms of some of the species in this genus are used as a source of food or indigestible fiber. In either case, the corm has to be processed properly to remove calcium oxalate crystals.

Smaller specimens can be grown as houseplants, or in a shady, woodland border in warm climates. Many of the large varieties can be seen in greenhouses at botanical gardens. Visitors flock to botanical gardens when Amorphophallus titanum produces an inflorescence. It has the largest unbranched inflorescence of any plant and the odor it produces when the flowers are open is that of a decaying corpse.

Insects, Diseases, and Other Plant Problems: No significant problems except collar rot caused by Sclerotium rolfsii. Corms can rot if the soil is kept too wet. Mealybugs can attack some plants.