Pachyrhizus ahipa aka Yam Bean

Pachyrhizus ahipa belongs to the pea family. Its names include ahipa and yam bean. Kew places its native range in western and southern Bolivia. This range extends into northwestern Argentina. Growers raise it for food in the Andes. Sources do not report plants growing in a truly wild state. Its main crop is a swollen root that people eat. Markets sell these roots at local and national levels.

This herb lives for years and grows from a tuberous rootstock. This is a thick root base. Some forms grow upright; others twine and climb. Upright plants reach about 0.5–2 feet [0.15–0.6 metres]. Twining stems can reach 6.6 feet [2 metres] long. They spread across the ground or climb nearby plants. Flowers have both male and female organs. Insects pollinate them. Plants can also pollinate their own flowers. They start to bloom about ten to eleven weeks after sowing. The plant also fixes nitrogen.

Give ahipa full sun and rich soil that drains well. Sandy or loamy soil suits it best. It prefers mildly acid soil but accepts a wider pH range. Plants can cope with drought. Yet moist soil gives better root crops. Ahipa grows in tropical and subtropical climates. Frost can harm it. Cooler regions may allow a summer crop. But it needs a long season free from frost. Greenhouse trials in Denmark have yielded good crops. Roots do not need short days to form. Harvest comes about five to six months after planting.

Growers remove flowers to get larger roots rather than seeds. To grow it from seed, soak seeds in warm water. Leave them for twelve hours. Sow under warm cover in early spring. Seeds should sprout in about two weeks. Move plants outdoors after the last expected frost. Young plants may need cover until they take hold. Growers can also divide the tuberous roots in autumn. Keep stored roots cool and free from frost through winter.

People can eat the root raw or cooked. Cut flesh stays crisp and is slow to brown. This makes it useful in fruit and green salads. Safety guidance differs for the plant's other parts. PFAF says people can eat young pods after thorough cooking. Useful Tropical Plants treats only the root as safe. Seeds and green parts contain compounds that may be poisonous. These are probably rotenone. Do not treat them as ordinary vegetables. Rotenone may also give the plant value for killing insects. It can harm useful insects, fish, and amphibians.