Family: Dioscoreaceae

This tropical, tuberous genus has a large, thick­ened trunk, or tuber, sometimes above ground, covered in thick, corky hark, growing to 1 m (3 ft) in diameter, and sometimes up to 50 cm (20 in) tall. This fleshy caudex produces annual, twining shoots which become woody. The glossy, green, veined leaves are triangular to heart-shaped, and sometimes lobed. Flowers are inconspicuous. Some Dioscorea are grown in tropical regions as a staple food.

Species

D. elephantipes is the best known species in Europe. Others may not be available.

D. alata, white yam or water yam, is grown as a staple food in its native Asia. It can produce huge tubers.

D. elephantipes, Hottentot bread or elephant's foot, has a hemispherical trunk base, growing up to 1 m (3 ft) in diameter, and covered with bark divided into rough, symmet­rically rounded segments, and glossy, heart-shaped leaves, with tessellated veins.

D. trifida, cush-cush or vampee, from tropical America, produces several individual tubers.

Cultivation

In frost-prone climates, grow in an intermediate to warm conservatory or green-house, in pots of soil-based potting compost. Provide maximum light but shade from direct sun. The stems will need supports. When dor­mant, keep plant only barely moist, but water normally otherwise. Outdoors plant in deep, well-drained soil with full sun. Propagate from seed, germinated at 24°C (75°F).

Climate

Zone 10 for most species.