Lablab

Lore & Background

The genus Lablab was established by Robert Sweet, taking its name from the earlier Dolichos lablab named by Carl Linnaeus. The specific epithet comes from the Arabic word lablāb. According to biologist Bernard Verdcourt, the species Lablab purpureus includes two cultivated subspecies—Lablab purpureus subsp. bengalensis and Lablab purpureus subsp. purpureus—and one wild subspecies, Lablab purpureus subsp. uncinatus, with a variant having lobed leaflets found only in Namibia: Lablab purpureus var. rhomboïdeus.

The plant is a variable annual or short-lived perennial vine, with thick stems reaching up to 6 meters. Leaves consist of three pointed leaflets, and flowers appear in racemes, colored white, purplish, or blue. The fruit is a legume pod, usually several centimeters long, ranging from bright purple to pale green, containing up to four seeds that vary in color—white, brown, red, or black—with wild plants having mottled seeds.

The exact origin of the lablab bean remains uncertain, with evidence of wild varieties in eastern and southern Africa suggesting those regions as the likely source, though some theories propose India. It has been distributed worldwide and can grow in temperate climates such as Central and South America or Italy.

Reader's Guide

Lablab is significant as an old domesticated pulse and multi-purpose crop, cultivated in India as early as 2500 BC. It is grown primarily for food and fodder, especially in tropical and subtropical areas of eastern and southern Africa and India, though its cultivation has declined in many African regions due to replacement by common bean and factors like processing steps and antinutritional elements. The plant's adaptability to a wide range of soils and climates, including tolerance of drought and shade, increases its agricultural value. Its symbiosis with nitrogen-fixing rhizobium bacteria improves soil nitrogen availability, making it attractive for intercropping and green manure. Researchers note the wide diversity of lablab germplasm holds potential for developing it as an alternative crop through selection and breeding. Breeding efforts aim to create varieties with simultaneous seed development for industrial farming, though this can shorten the vegetative phase and reduce yield. The fruit and beans are edible only after thorough boiling with several water changes, as they contain cyanogenic glycosides that can cause poisoning. Leaves, flowers, and roots are also used as food, and seeds are made into tofu and tempeh. In South Asia, the green pods and beans are cooked in various dishes, such as curries, stir-fries, and sambar.

Did You Know?

• The genus name Lablab was given by Robert Sweet from the earlier name Dolichos lablab by Carl Linnaeus, with the epithet coming from Arabic lablāb.
• There are two cultivated subspecies and one wild subspecies of Lablab purpureus, with a variant having lobed leaflets found only in Namibia.
• The plant can tolerate temperatures as low as 4 °C for short periods but is intolerant of waterlogged or flooded conditions.
• The fruit and beans are toxic if not boiled thoroughly with several water changes due to cyanogenic glycosides.