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Dioscorea. } DIOSCORLACEE (Baker). 247 
7 
Distris. Cosmopolitan, mainly tropical or subtropical. Genera 8. Species 
under 200. : 
I. Dioscorea. Tuber fleshy, subterranean. Seed winged all round or (§ Helmia) 
at the base only. 
Il. Testudinaria. Tuber large, firm, half-exposed. Seed winged only at the 
apex, 
I. DIOSCOREA, Linn. 
Flowers dicecious. Male perianth campanulate, with a short tube 
and 6 subequal oblanceolate segments. Stamens usually 6, inserted in 
the perianth-tube, sometimes only 3, the three inner abortive or 
entirely absent ; filaments short, incurved ; anthers oblong or globose. 
Style rudimentary. Female perianth smaller, with minute stami- 
nodes usually present, Ovary linear-triquetrous, 3-celled ; ovules 2 
in a cell, superposed ; style very short; stigmas 3, falcate, entire or 
bifid. Capsule oblong or obovate, rigidly coriaceous, acutely 
triquetrous, Seeds discoid, winged all round or (§ Helmia) at the 
base only. 
Rootstock a hypogeous tuber; stems twining; leaves simple or compound, 
usually alternate ; flowers small, greenish-yellow, spicate, racemose or panicled. 
The sections to which species belong, which have not been seen in fruit, 
cannot be determined. 
Distrrs. Cosmopolitan. Species about 150. 
Leaves simple, not lobed : 
Leaves shallowly cordate : 
Leaves twice as long as broad, 3-nerved «-» (1) Burchellii. 
Leaves as long as broad, 5-nerved iad .. (2) malifolia. 
Leaves deeply cordate : 
Leaves acute ; basal sinus broad é w. (3) Mundi. 
Leaves obtuse; basal lobes. touching or ..» (4) Behmanni. 
Leaves simple, lobed : 
Male flowers subspicate : 
Leaves palmate ... ia ee Hs ... (5) multiloba, 
Leaves cordute-ovate with a large central lobe : 
Stamens6 ... a oak ae sae “ diversifolia. 
Stamens 3... ae sa a .. (7) rupicola. 
Male flowers racemose... “a eae eae ... (8) undatiloba. 
Leaves compound : 
Leaflets 3; flowers panicled : 3 
Male flowers longer, not crowded a «.» (9) dregeana. 
Leaflets 5 ; flowers panicled: 
Leaflets sessile : : 
Outer leaflets large, deeply lubed ... ... (10) microcuspis. 
Outer leaflets small, entire ee, ... (11) Forbesii. 
Leaflets stalked : _ 
Pedicels very short: 
Bracts Saath longer than the flowers... (12) crinita. 
Bracts as long as the flowers ... .-» (13) retusa. 
Pedicels 1—} in. long se iy .» (14) Tysoni. 
1. D. Burchellii (Baker in Journ. Bot. 1889, 1) ; stems slender, very 
twining, glabrous; leaves alternate; petiole $4 in. long ; blade 
simple, ovate-lanceolate, shallowly cordate at the base, always entire, 
mucronate, 1-2 in. long, moderately firm in texture, bright green, 
triplinerved ; male flowers in lax subspicate racemes 1-2 in. lorg 
