Cajanus cajan

Pigeon pea is one of humanity's oldest crops and one of the best working plants in an agroforestry system: it fixes nitrogen, breaks up compacted soil with its deep roots, and gives shade, firewood and green manure. And it feeds you too: the young seeds are cooked like peas and the dry ones in soups and stews, as in the classic Caribbean rice with pigeon peas. It's a short-lived shrub up to 4 meters tall, very drought resistant. Wherever pigeon pea grows, the soil improves.

It grows in the tropical lowlands up to about 1,500 meters. It wants full sun and any well-drained soil, even a poor one; once established it's very drought tolerant thanks to its deep taproot. It dislikes very acid soils. It lives 1 to 5 years. Dwarf varieties are harvested from 5 months, tall ones at 8–12 months, over several months. Planting distance: 1–2 m.

The young seeds are cooked like peas, and the dry ones go into soups, stews and rice; they can also be sprouted or made into tempeh and tofu. Green pods are eaten in curries. The cooked leaves and young shoots are rich in protein, though their strong flavor isn't for everyone.

Traditionally a leaf infusion is used for coughs and bronchitis, leaf juice for diarrhea, and boiled leaves are applied to sores and wounds to help them heal. A flower and leaf infusion is used as a diuretic.

A placenta support species, one of the most useful for starting a system: it fixes nitrogen, its roots break up hardpans and improve infiltration, and its falling leaves add organic matter. It's pruned at 50–100 cm and the biomass left as mulch. It also serves as a windbreak, a shade crop and a support for vanilla.