518 
CIII. DIOSCOREACEiE 
Climbing plants ; root tuberous ; tubers large, especially in 
the cultivated species ; stems leafy, sometimes prickly, twining 
to the left. Leaves usually alternate, stalked, digitately 3-5-folio- 
late or lobed or simple ; margins entire ; basal nerves 5-9, promi- 
nent, curving outwards, veins netted. Flowers minute, bracteate, 
1 -sexual, in slender, axillary spikes or racemes, the male and female 
usually on different plants. Perianth persistent, regular, 6-parted ; 
segments nearly equal, in 2 series. Male flowers : stamens 6, at 
the base of the segments, sometimes only 3 bearing anthers, fila- 
ments free. Female flowers : perianth on the top of the ovary ; 
ovary 3-sided, 3-celled, ovules 2 in each cell, styles 3, short. Cap- 
sule hard, leathery, 3-winged, opening by 3 valves ; seeds flattened, 
winged. 
The plants are’ often propagated by small, scaly buds or bulbils borne in 
the axils of the leaves or flower-bracts, which fall to the ground, strike root 
and grow into independent plants. The leaves of some species closely resemble 
those of Smilax, but their flowers are in spikes or racemes, not in umbels, and 
the fruit is capsular not berried. 
Two species are commonly cultivated in the N.W.P. for their tubers called 
yams : D. sativa and D. globosa. 
Leaves digitately divided. Male flowers racemed . 
Leaves undivided. Male flowers spiked. 
Male spikes solitary. ..... 
Male spikes clustered. 
Spikes 1-1 b in. Perianth-segments ovate 
Spikes 3-6 in. Perianth-segments linear 
1. Dioscorea kumaonensis, Kunih ; FI. Br. Ind . vi. 290. 
Leaves glabrous or nearly so, usually alternate, 3-5 foliolate ; 
leaflets narrowly lanceolate, l-3xj-f in., tip finely acute. 
Inflorescence pubescent. Male flowers in racemes 1-2 J in. long : 
anther-bearing stamens 3, staminodes 3 ; pistillode erect, club- 
shaped. Female flowers hi spikes 2-6 in. long. Capsule J in., 
oblong, ends rounded ; seeds winged at the top. (Fig. 174.) 
Simla, below Sipi, 5000 ft. ; July. — Temperate Himalaya, 4000-8000 ft. 
The bulbils of this plant are peculiar in structure ; the outer coat is black 
and coriaceous or crustaceous, and inside is a flat body having the appearance 
of a seed ; the whole simulating a fruit. 
2. Dioscorea deltoidea, Wall. ; FI. Br. Ind. vi. 291. Glabrous 
or nearly so. Leaves usually alternate, variable in shape and size, 
general outline ovate-lanceolate, 2-6xlJ-4| in., long -pointed, 
widely cordate, the basal lobes often rounded and projecting ; 
stalks sometimes 10 in. Spikes solitary. Perianth-segments 
broadly oblong. Male spikes 3-15 in., very slender : flowers in 
small, distant clusters ; stamens all anther-bearing. Female spikes 
6 in. Capsule f-1 in., wings broadly rounded ; seeds usually 
winged all round, but sometimes only on one side. 
Simla, Narkunda ; May-July. — Temperate Himalaya, 6000-10,000 ft. — 
Afghanistan. 
1. D. kumaonensis. 
2. D. deltoidea. 
3. D. glabra. 
4. I). sativa. 
