Common Name: Pigeon Pea

General Information

Cajanus cajan is a short-lived, erect, woody shrub growing about 4 metres tall with erect ribbed, densely pubescent stems[].
Not known in the wild, the plant is often grown in the tropics and subtropics for its wide range of uses, including food, medicine and fuel. It is also often used as a green manure and for soil stabilization. This species is believed to be one of the earliest of cultivated crops. It arose through cultivation, possibly from Atylosia spp[, , ].

Known Hazards

None known

Botanical References

Range

E. Asia - India.

Habitat

Not known in a truly wild situation. It is , however, sometimes found in grassy habitats in savannahs, shrubland and waste land[].

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Shrub
Height	4.00 m
Pollinators	Self, Bees, Insects
Self-fertile	Yes
Cultivation Status	Cultivated

Cultivation Details

Grows well in lowland tropical areas up to an elevation of 1,500 metres, though some forms can still do well up to 2,000 metres[]. Plants generally prefer a rainfall in the region of 500 - 1,000mm per year, though there are some cultivars that are adapted to wet, humid tropics so long as the soil is well drained[]. A temperature range of 20 - 30°c is preferred, but under optimal cultural conditions good yields can be obtained with temperatures up to 35°c[].
Grows best in a sunny position[]. Succeeds in a wide range of soils that are well-drained[]. Plants produce deep tap roots, they can succeed in poor soils and are extremely drought resistant once established[, ]. Dislikes very acid soils, growing best in a pH range of 5.5 - 6.5[].
A short-lived, woody plant, dying after 1 - 5 years[].
Harvesting of dwarf varieties can commence 5 months after sowing (8 - 12 months for taller varieties) and continue for several months[].
A relatively low-yielding crop, yields of up to 5 tonnes per hectare of pods, or 1 tonne of seeds can be achieved[, ].
In perennial crops, 2 - 10 tonnes per hectare a year of woody stalks can be harvested for fuel[].
There are two main forms of this plant, and many named varieties of each[, , ].
Var. Flavus DC. Is a moderate height plant that is early maturing, it is often grown as an annual in India[]. The green pods normally contain 3 seeds[].
Var. Bicolor DC. Is a taller plant that is later to mature and is usually grown as a perennial[]. The dark coloured pods contain 4 - 5 seeds[].
Short-duration dwarf cultivars are usually daylength neutral, but the taller growing cultivars are usually short-day plants that will not readily flower if day length is 12 hours or more[].
A good companion plant, it is often grown in association with other crops[].
This species has a symbiotic relationship with certain soil bacteria, these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby[].

Edible Uses

Seed - cooked. Very young seeds can be cooked and eaten like peas, going well in rice dishes[, ]. Mature seeds are dried and added to soups and stews[, ]. Small but flavourful[]. The seed may be used instead of soya bean to make tempeh or tofu, and can also be sprouted and eaten when about 25mm long[, ]. The seed is usually round or oval and up to 8mm in diameter[].

Young seedpods - cooked[, ]. The unripe pods are eaten in curries[]. The pods are up to 10cm long and 14mm wide[].

Leaves and young shoots - cooked and used as a vegetable[, ]. A strong, spicy odour, with a new flavour that is not agreeable to everyone[]. A good source of protein[]. The leaves contain up to 9% protein[]. The leaves quickly become fibrous[].

Medicinal

The roots are anthelmintic, sedative, expectorant and vulnerary[].

An infusion of the leaves is used as a treatment for pulmonary conditions such as coughs and bronchitis[]. The leaf juice is taken internally in the treatment of haemorrhages, coughs and diarrhoea[, ]. An infusion of the leaves, combined with Dactyloctenium aegyptium, is used to accelerate childbirth[].
Young leaves are chewed to treat boils on the tongue[]. A decoction is used for washing ulcers[]. The boiled leaves are applied to sores and wounds to hasten cicatrization[].

Young shoots and the green seedpods are used to make a good pectoral infusion[].

An infusion of the flowers and leaves is diuretic and is used as a diabetes remedy[].

An infusion of the flowers is pectoral[].

A decoction of the plant is diuretic and laxative[]. It is used in the treatment of sore throats[].

An infusion of the seeds is diuretic[]. A flour made from the seeds is resolutive[].

Leaf contains cholesterol[].
The root bark contains numerous flavones including cajaflavanone and cajanone, and triterpenes[].
The root contains cajanone, an antimicrobial agent[].
An enzyme called 'urease' can be extracted from the plant. It has medicinal applications[].

Agroforestry Uses:

A good green manure crop[, ].
The plant has an extensive root system and is often grown to bind soil[, ]. It is also grown to provide shelter from the wind[]. It is also grown as a shade crop, cover crop, or as support for vanilla[].
Due to its hardiness, ability to grow on residual soil moisture, and slow early growth, this species is an ideal, non-competitive crop to plant with cereals[].
For hedgerow intercropping, the hedges should be cut at height of 50 - 100cm when the grain crop is fully mature. The hedges can be cut 2 - 3 times a year in areas where the dry season lasts 4 - 6 months. At pod maturity, the branches are cut at about 50cm. Higher levels of pruning can result in higher and unacceptable levels of plant mortality[].
The root system is reported to break plough pans, thus improving soil structure, encouraging infiltration, minimizing sedimentation and smothering weeds. Leaf fall at maturity adds to the organic matter in the soil and provides additional nitrogen. It seems to have special mechanisms to extract phosphorus from black Vertisol soils[].
The plant improves the soil through its extensive root system, nitrogen fixation and the mulch provided by the fallen leaves.

Other Uses

The stems are of use in basketry and thatching[]. The plants are often used as brooms[].

An essential oil can be collected by the steam distillation of the leaves and other aerial organs. It contains a mixture of compounds including the terpenoid alpha - copaene[].
The macerated leaves are used as a deodorant[].

The wood is used in light construction such as in roofing, wattling on carts, tubular wickerwork lining for wells and baskets[].
The dried stalks and branches are used for fuel[]. The sticks are an important household fuel in many areas. The heat value, with 1,450 kJ per 100g, is about half as high as the same weight of coal[].

Propagation

Seed - sow in situ during the wet season, placing the seed 2 - 3 cm deep in the soil[]. Two seeds are often planted per station, thinning to the best plant[]. The seeds germinate at temperatures of 19 - 43°c, but most rapidly at 20 - 30°c. Emergence is complete 2 - 3 weeks after sowing. Vegetative development starts slowly, but after 2 - 3 months growth accelerates[].

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Captcha: if i have 3 bananas, and i eat them all, how many bananas did i just eat?