Dioscoreaceae

Rhizomes (rarely spiny) producing annual, mostly twining shoots, in Malaysia twining either to the right (fig. 4c) or the left (fig. 4a). Stems consisting of a main stem and sterile branches, both bearing leafless flowering axes. Leaves petiolate, generally cordate, simple and entire or palmately lobed, or palmately compound, except in the latter triplinerved; apex generally glandular, developed before the blade (forerunner tip); blade usually glandular on the lower side chiefly towards the base. Flowers hermaphrodite or dioecious, ♀ with staminodes, ♂ without even a rudimentary ovary, actinomorphic, 3-merous, mostly inconspicuous and greenish, ♂ often massed together and scented. Tepals in two whorls of 3. Stamens in 2 whorls of 3, the inner sometimes sterile; anthers usually introrse. Torus an urceolate, perianthoid chamber in Stenomeris, a saucer or cup in many spp. of Dioscorea, fleshy in Dioscorea § Enantiophyllum, in some spp. enlarged into a cone making the stamens appear to be connate. Style 1 with 3 bifid stigmas. Ovary 3-locular, inferior, sometimes separated from the perianth by a constriction. Ovules 2 in each cell or ~ (in Stenomeris), anatropous. Fruit a capsule, but it breaks up rather than dehisces in Trichopus. Seeds winged or wingless (in Trichopus); endosperm horny, embryo in a marginal pocket. Distr. Ca 9 genera and about 600 spp. (Dioscorea large, the other genera small or monotypic). Pantropic with considerable extensions into temperate regions. The Stenomerideae and Trichopodeae are restricted to the warm humid regions where Nepenthes grows and their geologic history must have been that of Nepenthes: they may be regarded as the survivors of the hermaphrodite ancestry of the Dioscoreeae.