Fiveleaf Yam

Dioscorea pentaphylla is an extremely widespread and variable species, such that Prain and Burkill recognized a total of 16 varieties in their revision of Asian species of Dioscorea. Synonyms based on material from outside China are not listed here. Dioscorea changjiangensis was recently described from an apparently distinctive collection from Hainan, but, when this is considered within the total range of variation shown by the species, we believe that it has to be included within D. pentaphylla. Dioscorea codonopsidifolia known only from the type collection from N Taiwan, is also included here for similar reasons. Most Chinese material has a reddish brown indumentum but this is not constant for the species throughout its range.

Tubers irregular, usually long ovoid; transverse section white when fresh, becoming brown; roots fibrous. Stem twining to left, sparsely puberulent, glabrescent, prickly. Bulblets present. Leaves alternate, palmately 3--7-foliolate; petiole 5--11 cm, densely reddish brown pubescent; leaflets ovate to lanceolate, 6.5--24 × 1.5--9 cm, adaxially glabrous, abaxially appressed pubescent, sometimes glabrescent, pinnately veined, base attenuate into a ± tomentose petiolule, margin entire, apex acute. Male spikes in axillary panicles to 50 cm, often with long, lateral branches; axis brown pubescent. Male flowers: sessile or subsessile; bract and bracteole reniform, forming an involucel around perianth, sparsely hairy, apex cuspidate; stamens 3. Female spikes simple or branched, brown puberulent. Female flowers: bracts, perianth, and ovary hairy. Capsule black at maturity, long ellipsoid, 2--2.5 cm, thinly leathery, sparsely hairy; wings 0.5--0.6 cm wide. Seeds inserted near apex of capsule; wing pointing toward capsule base. Fl. Aug--Oct, fr. Nov--Feb.

Himalaya (Simla to Mishmi Hills), India, Burma, Thailand, Indo-China, China (Yunnan to Kwantung), Malaysia.

S Fujian, Guangdong, Guangxi, S Hunan, S Jiangxi, Taiwan, SE Xizang (Mêdog Xian), Yunnan [Bangladesh, India, Indonesia, Japan (Okinawa), Laos, Malaysia, Myanmar, Nepal, New Guinea, Philippines, Vietnam; Africa, Australia, Pacific Islands].

600-1500 m

Scrub forests, forest margins; 500--1500 m.

Dioscorea changjiangensis F. W. Xing & Z. X. Li; D. codonopsidifolia Kamikoti.

Dioscorea pentaphylla is a species of flowering plant in the yam family known by the common name fiveleaf yam. It is native to southern and eastern Asia (China, India, Indochina, Indonesia, Philippines, etc.) as well as New Guinea and northern Australia. It is widely cultivated as a food crop and naturalized in Cuba and on several island chains in the Pacific (including Hawaii).

Dioscorea pentaphylla is a prickly vine that twines counterclockwise around objects and other plants. It may reach 10 meters in length. The alternately arranged leaves are compound, divided into 3 to 5 leaflets each up to 10 centimeters long. The plant produces horseshoe-shaped bulbils about a centimeter long. New plants can sprout from the bulbils. Flowers are borne in spikes. The vine grows from a tuber. Specimens may weigh 3 pounds and may be located over a meter underground.

The tubers of the vine can be cooked and eaten.