Dioscoreaceae

By: Kusum Gurung & Ram P. Chaudhary

Geophytic, herbaceous climbers. Underground parts a perennial or annually replaced horizontal or vertical, one to several, variable shaped tubers. Trichomes simple or branched or absent. Stems twining to left or right, towards base often woody and spiny or unarmed, terete or winged, surface smooth or with longitudinal ridges. Leaves alternate, opposite or subopposite, petiolate, or pulvinus at each end, simple or palmately compound, lateral nodal flanges sometimes present. Primary venation campylodromous, pinnate or palmate; secondary venation reticulate. Bulbils present in leaves axil or absent. Inflorescences usually axillary, panicles or cymes, spikes, or racemes. Flowers bracteolate, unisexual, subsessile or sessile, trimerous, actinomorphic, epigynous. Tepals 6, in 2 whorls of 3, variable colors. Torus short, broad and flattened. Male flowers: stamens usually 6, sometimes 3 fertile stamens and 3 staminodes. Filaments free, inserted at base of tepals or on torus. Pistillode present as erect column, 3-lobed or absent. Female flowers: gynoecium syncarpous, tricarpellate, trilocular, staminodes 6 or rarely absent; placentation axile. Styles 3, free or fused; stigma 1 or 3-lobed, frequently papillate, recurved (backward) or bifid. Fruit a 3-winged capsule, dehiscence loculicidal. Seeds 2 per locule, flattened and winged.

Worldwide four genera and 641 species.

One genus (Dioscorea) and 13 species in Nepal.

Number of genera and species in the family, and the number of species in the genus are cited from the ‘Flowering Plants of the World’ (Christenhusz et al, 2017).