Closely related to Canavalia gladiata[]. The species differ as follows:- The seeds of this species are white, with a hilum that extends to less than half the length of the seed (red in Canavalia gladiata, with a hilum that extends nearly the whole length of the seed); the pod shape is more curved in Canavalia gladiata; flower size and colour differ – purple in this species, pink or white in Canavalia gladiata.

Common Name: Jack Bean

General Information

Jack bean is an annual to short-lived perennial plant that can be bushy or climbing in habit[]. It usually grows 50 - 200cm tall but can become up to 10 metres long when climbing, its stems supporting themselves by twining around other plants[].
The plant has a long history of cultivation, with records showing the crop has been grown in Mexico since around 3,000 BC. It is often grown in tropical and some subtropical and temperate areas, usually as an annual crop and mainly in Japan and southeast Asia, for its edible seeds and seedpods, and also as a cover crop[, ].

Known Hazards

The mature seeds contain toxic alkaloids. These can be destroyed by thoroughly boiling the seeds twice in salt water[]. Toxicity may occur in cattle grazing jack bean aftermath and consuming too much seed meal[].

Botanical References

Range

Central America, Caribbean.

Habitat

Not known in a truly wild situation

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Annual/Perennial
Height	1.00 m
Pollinators	Insects, Self
Self-fertile	Yes
Cultivation Status	Cultivated

Cultivation Details

The plant can be grown in temperate to tropical areas at elevations up to 1,500 metres[]. It grows best in areas where annual daytime temperatures are within the range 20 - 28°c, but can tolerate 14 - 36°c[]. The foliage is intolerant of frost, but mature beans are unaffected[]. It prefers a mean annual rainfall in the range 800 - 2,000mm, but tolerates 600 - 4,300mm[].
An easily grown plant, it is not fussy about soil type or fertility, though it prefers a soil rich in organic matter[]. Plants prefer a sunny position, but are somewhat shade tolerant[]. A deep rooted plant, it is drought resistant when established[]. Prefers a pH in the range 5 - 6, tolerating 4.3 - 8[].
Young pods can be harvested about 4 months after sowing[]. Green pods can be harvested after 80 - 120 days, and mature seed after 180 - 300 days[].
Yields of about 1 - 1.3 tonnes of dried seed can be obtained[]. The optimum yield is 5.4 tonnes/ha of dry seed, while the average yield is about 1.3 tonnes/ha[].
40 - 50 tonnes/ha of green manure/green vegetation can be obtained[].
A short day plant, often developing a bushy habit, but more commonly a climbing plant[].
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[]. When removing plant remains at the end of the growing season, it is best to only remove the aerial parts of the plant, leaving the roots in the ground to decay and release their nitrogen.

Edible Uses

Young seedpods - raw or cooked[]. Very young seedpods, before the seeds swell within, can be eaten raw[]. They are also cooked like french beans and used as a vegetable[, , ]. The pod is 20 - 30cm long and 2cm wide[].

Seeds - cooked[]. Unripe seeds are cooked and eaten like broad beans[]. Thorough boiling is necessary in order to destroy a toxic alkaloid[]. The seed is about 20mm long[]. (The report actually says that the seed is 20mm x 130mm, but this is surely a misprint[].)
The roasted seed is used as a coffee substitute[, ].

Young leaves - cooked[]. Used like spinach[].

Medicinal

The plant has medicinal properties[].

Agroforestry Uses:

The plant fixes atmospheric nitrogen and often has a spreading habit. It is cultivated as a cover crop to conserve and fertilize the soil for other crops[].
The plant is grown as a green manure[].

Other Uses

None known

Propagation

Seed - sow in situ, placing the seeds 2 - 3cm deep in the soil[]. The seed germinates in about 72 hours[].

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