414 CXXXIX, DIOSCOREACE® (BAKER). | Dioscorea. 
Order CXXXIX. DIOSCOREACEM. (By J. G. Baker.) 
Flowers regular, usually dicecious. Male flowers: Perianth cam- 
panulate ; tube very short; segments 6, biseriate. Stamens inserted at 
the base of perianth, 6 all perfect or 3 reduced to staminodia ; filaments 
short ; anthers 2-celled, dehiscing longitudinally ; pistil rudimentary. 
Female perianth cut down to the ovary. Staminodia usually present. 
Ovary inferior, 3-celled ; ovules 2 in a cell, superposed ` styles 3, very 
short, stigmatose at the apex. Fruit capsular, rarely baccate. Seeds 
usually flattened and winged ; albumen fleshy or cartilaginous ; embryo 
minute.—Rootstock large and tuberous. Stems usually twining, some- 
times prickly. Leaves simple or compound, with reticulated venation. 
Flowers small, greenish, usually spicate. 
Species about 160, spread through the warmer zones of both hemispheres. 
1. DIOSCOREA, Linn.; Benth. et Hook. f. Gen. Pl. iii. 742. 
Flowers dicecious. Male perianth with a very short tube and 6 
subequal biseriate segments. Stamens 6 all perfect or 3 reduced to 
staminodia, shorter than the perianth. Pistil rudimentary. Female 
flowers with a similar perianth, 3 short styles and an oblong triquetrous 
ovary. Capsule rigid, deeply 3-lobed, in the subgenus Hudioscorea. 
broader than long, with orbicular seeds winged all round the nucleus, 
and in the subgenus Helmia oblong with the wing of the seed only 
produced on the lower side of the nucleus.—Rootstock large and 
tuberous. Stem twining. Leaves distinctly petiolate, opposite or 
alternate, simple or compound, often with bulbils in their axils. 
Flowers small, arranged in dense or lax spikes or racemes, solitary or 
fascicled, produced from leafy or leafless nodes. 
Species about 150, spread through the warmer zones of both hemispheres. 
Leaves simple, all alternate. 
Leaves and flowers glabrous. 
Male spikes (or racemes) simple. 
Leaves cordate. 
Perianth-segments linear 
Perianth-segments acute 
Leaves sagittate : S S $ : : 
Male racemes with lower pedicels bearing 2-3 
flowers : - : e ‘ s . 4. D. hylophila. 
Male spikes panicled S S : ` 5. D. macroura. 
Leaves beneath and flowers hairy. 
Spikes or racemes short. 
Leaves grey-pubescent beneath 
Leaves ferrugineo-tomentose beneath 
Spikes or racemes very long 
Leaves simple, usually opposite. 
Stem quadrangular, 4-winged. 
Flowers glabrous : : : ; : . 9. D. alata. 
Flowers tomentose . e e . 10, D. colocasiafolia. 
D. sativa. 
D. Buchanani. 
. D. sagittata. 
be tl bee 
. D. hirtiflora. 
. D. rubiginosa. 
. D. Preussii. 
DND 
