Description from Flora of China
Dioscorea alata var. purpurea (Roxburgh) A. Pouchet; D. purpurea Roxburgh.
Tubers variable, usually globose or conical (when cork brown or purplish black and transverse section purplish white), or oblate or cylindric, much branched (when cork brown or grayish yellow and transverse section white). Stem twining to right, glabrous, ridged, with 4 narrow, membranous wings, prickly at base. Bulblets present, variable in shape. Leaves alternate basally on stem, opposite distally on stem, simple; petiole green or purplish red, 4--15 cm; leaf blade green or purplish red, ovate, 6--15(--20) × 4--13 cm, papery, glabrous, base sagittate to deeply cordate, apex shortly acuminate or caudate. Male spikes solitary or a few together, 1.5--4 cm, sometimes forming a panicle; rachis obviously zigzagged. Male flowers: outer perianth lobes broadly ovate, 1.5--2 mm; stamens 6. Female spikes solitary or 2 or 3 together. Female flowers: staminodes 6. Capsule not reflexed, oblate, sometimes obcordate, 1.5--2.5 cm; wings 1.2--2.2 cm wide. Seeds inserted near middle of capsule, winged all round. Fl. Nov--Jan, fr. Dec--Jan.
Cultivated. Guangdong, Hubei [probably originated in cultivation in SE Asia; now cultivated pantropically].