ຫົວກອຍ / Asiatic Bitter Yam

Koi is a perennial climber up to 2 m long, with stems twining to the left, with thorns, and a system of fibrous roots, some of which develop into small round tubers when young. These stretch when mature, but remain ball-shaped and can reach 30 cm in diameter and 35 kg in weight. The lobed tubers are brown and covered on the outside with fibrous rootlets that are straw to light-grey coloured. The raw, poisonous flesh is white to lemon-yellow in colour. The stems are 9 mm in diameter, usually prickly, and green to straw-coloured. Leaves are sized 30 x 28 cm and contain three leaflets with spines on the large nerves on the back and a hairy lower surface. Male inflorescence are 50 cm long, bending downward, with yellow or pale-brown flowers covered with white hair. Female inflorescence are solitary. The winged fruit capsules are honey-coloured and measure 40-60 x 10-12 mm. The seeds also have wings. Four varieties occur in the Indochinese region: var. mollissima, var. scaphoides, var. hispida and var. dalmona. 12-15 species of yams grow wild in Indochina, with Dioscorea alata L. (Man Phao Khao) and D. bulbifera L. (Man Pao) often cultivated.