Dioscoreaceae

KEY TO SPECIES

1. Leaves simple

　2. Stems and petioles winged or quadrangular...............1. Dioscorea alata

　2. Stems and petioles neither winged nor anguled

　　3. Stems sinistrose

　　　4. Stems glabrous

　　　　5. pulvinus with a pair spines........................6. Dioscorea collettii

　　　　5. pulvinus auricled-clasped.......................4. Dioscorea bulbifera

　　　4. Stems prickly and with T-shaped villose............9. Dioscorea esculenta

　　3. Stems dextrorse

　　　6. Leaves alternate

　　　　7. Stems glabrous, leaves hastate-triangular...........8. Dioscorea doryphora

　　　　7. Stems prickly, leaves lanceolate...................10. Dioscorea formosana

　　　6. Leaves opposite, sometimes alternate near the base of stems

　　　　8. Leaves lanceolate or elliptic, acute or round at base

　　　　　9. Leaves coriaceous or subcoriaceous, staminate inflorescence paniculiform..........5. Dioscorea cirrhosa

　　　　　9. Leaves chartaceous, staminate inflorescence 1-3 spicate................3. Dioscorea benthamii

　　　　8. Leaves ovate-triangular or hastate lanceolate

　　　　　10. Leaves ovate-triangular, warped inward..............2. Dioscorea batatas

　　　　　10. Leaves narrowly triangular, oblong-triangular, plated........12. Dioscorea japonica

1.Leaves palmately compound

　11. Leaflets 3-7, lateral leaflets narrowly-obovate, oblique-acute at base, male flowers with pedicle.........................7. Dioscorea cumingii

　11. Leaflets 3, lateral leaflets oblique-obovate, round at base, male flowers sessile........................................11. Dioscorea hispida