Pachyrhizus erosus (L.) Urb.

Herbaceous vines; stems pilose, often drying hollow; rootstock tuberous. Leaves pinnate trifoliolate, the leaflets ovate to broadly ovate, the terminal leaflet broadest and often 3-7 lobed, the sinuses and lobes acute or rounded, mucronate, the lateral leaflets oblique, often less lobed or entire, basally deltoid, 3-veined from the base, drying slightly discolorous, glabrate or densely soft tomentose; petiolules 4-5 mm long, stout, pilose; petioles and rachis slender, drying angled, pubescent; stipels 1-2 mm long, acicular, sericeous, basally extended into definite ribs on the rachis; stipules minute, caducous. Inflorescences axillary pseudora-cemes, mostly 12-20 cm long, the flowers congested near the apex, the peduncle mostly longer and stouter than the petioles, the bracteoles resembling the stipels, subtending and much shorter than the calyx; pedicels ca. 2 per node, slender, ca. 5 mm long. Flowers blue, calyx 5-8 mm long, tubular, 2-lipped, the upper 2 teeth mostly connate, the lower 3 acute or acuminate, shorter than the tube, subequal or the lowermost longest and acuminate; standard ca. 15 mm long, suborbicular, emarginate, the wings and the keel about as long as the standard, sometimes ciliolate. Legume oblong, ca. 10 cm long, 1.5-2 cm wide, compressed, appressed strigose.

A tropical plant. It grows in warm places. It grows in coastal areas in Papua New Guinea and up to about 70 m altitude in the tropics. A well drained soil is needed. A light rich sandy soils is suitable. It cannot tolerate frost. Plants need 11-13 hours of daylight for tubers to form. A pH of 6-7 is suitable. It can grow in arid places. It suits hardiness zones 10-11. In Sichuan and Yunnan.

The young tuber is eaten either raw or cooked. They can be boiled, stir-fried, roasted, braised or used in soups. It can also be pickled. The tubers can be a source of starch used in custards and puddings. The young pods can be eaten. (They must be well cooked.) CAUTION Old pods and mature seeds can be poisonous.

It is grown from seeds and also grows wild. Seed should be presoaked for 12 hours in warm water to encourage rapid germination. Seed germinate within 2 weeks. Plants can be grown by dividing the root clump and growing plants from the thickened roots. Cuttings will grow. A spacing of 50 cm between plants is suitable. Topping the plant by picking out the growing point and removing the flowers is supposed to help tubers form.