Canavalia gladiata aka Scimitar Bean

Canavalia gladiata, or sword bean, belongs to the pea family, Fabaceae. It is a crop plant from tropical and subtropical Asia. Its exact wild origin remains unclear after a long cultivation history. Useful Tropical Plants suggests an eastern Asian origin. That source reports no known wild habitat for the species. People now grow it across tropical and some subtropical regions. They raise it for food and as a garden climber.

Sword bean can live as an annual or perennial vine. It has deep roots and strong, climbing stems. These may turn somewhat woody as they age. They trail across the ground or twine through nearby plants. Stem length can reach 33 feet [10 metres]. The source also lists a height of 3.3 feet [1 metre]. These figures do not establish a clear, usual garden height. Gardeners grow the vine along fences and beside houses.

The flowers can be pink or white. Insects pollinate them, and the plant can also pollinate itself. Its curved pods hold red seeds with a long hilum. This seed scar runs along almost the whole seed. Pods measure about 0.7–1 foot [0.2–0.3 metres] long. The seeds reach about 0.07 feet [0.02 metres] in length. Both the young pods and the seeds serve as food.

The plant grows well in warm, lowland tropical conditions. It also grows at elevations reaching 4,920 feet [1,500 metres]. Its best daytime temperature range is 15–30°C. Frost damages the leaves, though mature beans can remain unharmed. It accepts varied soils and does not need high fertility. Soil rich in organic matter suits it best. It tolerates shade and some salt in the soil. Once established, its deep roots help it withstand drought. It can also cope with some waterlogging. Growers can sow seeds straight into their growing site. The source reports germination in about three days.

Young pods are eaten as a vegetable, most often cooked. Mature seeds contain toxic alkaloids and need thorough preparation before eating. The source describes repeated boiling, with changes of water. Raw mature seeds are therefore not a safe food. The seeds also supply urease for laboratory blood tests. Traditional medicine uses are reported, but do not establish proven treatments.