The Jack bean (Canavalia ensiformis L.) is a climbing herbaceous species belonging to the Fabaceae family.
From a systematic point of view it belongs to the Eukaryota Domain, Plantae Kingdom, Subregion Tracheobionta, Magnoliophyta Division, Magnoliopsida Class, Rosidae Subclass, Fabales Order, Fabacee Family, Faboide Subfamily, Phaseoleae Tribe, Diocleinae Sub tribe and therefore to the Genus Canavalia and the Specie C. ensiformis. .
The term Canavalia is the Latinized form of the vernacular term of the Malabar kanavali, which means “forest climber”.
The specific epithet ensiformis refers to the character of the plant with sword-shaped foliage.
Geographical Distribution and Habitat –
Canavalia ensiformis is a native of southern and central America and has been found in archaeological sites in Mexico dating back to 3000 BC. circa (Smartt, 1985; Chee et al., 1992, USDA-ARS, 2016).
It grows in the tropics of both hemispheres, usually in cultivation, although it has fled and naturalized in some areas outside its native range.
Although in the humid tropics it thrives in the plains, C. ensiformis is also found at altitudes up to 1800 m where it prefers areas with annual rainfall between 800 and 2000 mm. It grows best at temperatures between 13 and 27 ° C.
Jack bean is a vine that grows slightly woody, dense, which reaches 1-2 m in length.
The stems are cylindrical, pubescent and then glabrescent, with the hollow marrow.
The leaves are alternate, trifoliate, with broadly ovate or broadly elliptical leaflets of 6-20 × 5-12 cm; they have obtuse or rounded apex, short apical, obtuse base, asymmetrical on the lateral leaflets and whole margins; both surfaces are dotted; cylindrical petiole and rachis, glabrescent; swollen petioles about 8 mm long.
The inflorescences are axillary pseudorachemes, 25-36 cm long, with 2-3 flowers grouped on the nodal swellings along the spine; the peduncles are 1-2 mm long, glabrescent. The chalice is green, bell-shaped, 12-14 mm long, bilabiate; pale purple corolla, about 2 cm, with white wings at the base, purple on the distal portion.
The fruit is a linear legume, up to 30 × 3.5 cm long, woody, slightly curved towards the apex, each valve with three longitudinal ribs.
The seeds, 15-20 in number, are ellipsoids, up to 3 cm long, white or cream colored.
Jack bean is a plant whose deep root system allows it to withstand periods of drought.
It is a mainly self-pollinated species, but it is also pollinated by ants and other insects, such as bees.
It produces pods in the lower part because only the two or three lowest flowers of the node of the inflorescence produce pods.
From the point of view of the cycle, it is an annual or short-lived perennial.
Canavalia ensiformis can grow continuously in difficult conditions, even in acidic and nutrient-poor soils, highly leached.
At high temperatures its leaves tend to fall and can tolerate light frosts.
It is widely cultivated in tropical countries for its ability to fix atmospheric nitrogen. In fact, its roots develop, like those of many similar species, a particular association with nitro-fixing bacteria forming root nodules and which is spontaneous enough in nature so as not to be sensitive to specific inoculation. The sowing of Canavalia must take place at the same time as that of its guardian (generally Sorghum) so that it develops rapidly and can be cut before it suffocates the plant with its lush vegetation and prevents the ripening of the panicles.
The leaves provide abundant ground cover, preserving humidity even in other crops.
Uses and Traditions –
Jack bean is an edible plant as a vegetable while for seeds, the presence of a mixture of toxic substances, of which a part is also resistant to cooking, does not recommend human consumption.
The seeds of Canavalia ensiformis, in fact, accumulate a considerable amount of canavanine (up to 2% on the dry basis), a substance – very similar to the amino acid arginine which has excellent potential as an insecticide, while remaining harmless for Vertebrates.
The whole plant is used for fodder, although it cannot be used in forage mixtures containing ure, as it contains large amounts of enzyme urease, which releases harmful ammonia.
For this reason, Canavalia ensiformis has been studied as a potential source of the urease enzyme. It is also a source of concanavalin A, a lecithin used in biotechnological applications, such as affinity chromatography for lectin.
The detoxified C. ensiformis seed has been used successfully as a substitute for high protein fishmeal in tilapia aquaculture.
Canavalia ensiformis, is one of the many tropical legumes studied for their potential as an alternative food source to help solve the problems of food insecurity and global hunger, as it is extremely resistant to difficult climatic conditions.
In Nigeria, C. ensiformis seed is used as an antibiotic and antiseptic.
There is also a pharmaceutical interest in the use of C. ensiformis as a source for the anticancer agent trigonelline and canavanine.
The leaves are scattered on leaf-cutting anthills to eliminate ants.
In general, Canavalia ensiformis is used as a soil enhancer and is planted for erosion control. It is used in conservative agriculture with corn and cassava and in Mauritius, it is used as a green fertilizer in the cultivation of sugar cane.
It has been reported as a nematode antagonist or suppressant, particularly when used in banana plantations, although this effect is not confirmed.
Method of Preparation –
Jack bean is a plant whose leaves can be eaten as a vegetable.
In order to be consumed, the seeds must undergo special cooking procedures to eliminate most of their toxic substances.
– Acta Plantarum – Flora of the Italian Regions.
– Wikipedia, the free encyclopedia.
– Treben M., 2000. Health from the Lord’s Pharmacy, Tips and experiences with medicinal herbs, Ennsthaler Editore
– Pignatti S., 1982. Flora of Italy, Edagricole, Bologna.
– Conti F., Abbate G., Alessandrini A., Blasi C. (edited by), 2005. An annotated checklist of the Italian vascular flora, Palombi Editore.
Warning: Pharmaceutical applications and alimurgical uses are indicated for information purposes only, they do not in any way represent a medical prescription; therefore, no responsibility is accepted for their use for healing, aesthetic or food purposes.