Vigna vexillata Seeds | Wild Cowpea

Wild Cowpea (Vigna vexillata) with twining stems, trifoliate leaves and pale pea-flowers — Wild Cowpea (*Vigna vexillata*): Fabaceae, the drought-proof wild cousin of the cultivated beans.

LATIN NAME: Vigna vexillata

COMMON NAME: Wild Cowpea

Plant Profile

The Wild Cowpea is a trailing and twining perennial of the pea family, spread across Africa, South Asia and Southeast Asia, and its habit is opportunistic: slender stems scramble through grass and over low shrubs to a metre or more, carrying trifoliate leaves and small pea-flowers in cream, purple or pink through the warm season. Below ground it holds a tuberous root, a storage organ that lets it stand drought, fire and grazing and re-emerge with the rains.

It grows on poor, sandy, disturbed ground across an enormous range, and its value is what it carries rather than what it shows: it is a wild gene-pool relative of the cowpea and the mung bean, two of the tropics’ staple crops, and its toughness is the trait breeders come to borrow.

Science & Biotechnology

Its scientific importance is in crop improvement: as a wild relative of Vigna unguiculata, the cowpea, it has been crossed into breeding programmes seeking drought tolerance, disease resistance and the tuberous root habit, and studies of its diversity across Africa and Asia have mapped the variation available to breeders. The genus Vigna holds the mung bean, the adzuki bean and the cowpea among its domesticates, and the wild species round out the gene pool with the resilience the crops have lost in domestication. Its root nodules fix nitrogen with the standard bradyrhizobia of the tribe, and its tuberous root is itself a documented famine food and folk medicine in parts of its range.

For the grower the practical point is hardiness: it stands the poor, dry ground that defeats its cultivated cousins, and it seeds itself into any warm, sandy bed.

Uses & Benefits

In the garden it is a quick, forgiving cover for a trellis, a fence or a bank, flowering through the warm season and fixing nitrogen as it goes. It is also worth growing as what it is: a wild relative of the kitchen beans, carrying the drought-proof toughness that domestication bred out of them, and a tuberous root that has fed people in hard years across its range.

Its flowers feed bees, its foliage can be cut as green manure, and its main service in a garden sense is as a demonstration of where the crops came from. In breeding programmes its uses are more serious, and the seed banks hold it accordingly.

Growing from Seed

Nick the hard seed coat lightly or soak in warm water overnight, then sow into a free-draining mix at 22 to 28 °C; germination follows within a week and the seedlings twine from the first month. Grow them in full sun on the dry side, potting on as they run, and give young plants a support to climb from the start.

Plant out into any poor to average soil in full sun after the last frost, spacing plants half a metre apart at the base of their supports. Water to establish only. It will flower and seed through the warm months, and in mild climates it persists from the tuberous root; in cold climates treat it as a vigorous annual and save seed.

Our Take

The wild cousin of the cowpea: twining, tuberous, drought-proof and flowering all summer. A nitrogen-fixing cover with a famine-food past and a breeding-programme future.

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