Common Name: Earthnut Pea

General Information

Lathyrus tuberosus is a herbaceous perennial plant growing from a rhizomatous rootstock that bears small tubers. It produces a cluster of erect stems that branch from the base; the plant growing 30 - 120cm tall[, ]. The stems scramble through surrounding plants, supporting themselves by means of tendrils[].
The plant is harvested from the wild for local use as a food. It has sometimes been cultivated as a food crop, though yields are rather low. Based on its palatability, however, it is certainly worthy of cultivation, especially if work is done to improve yields[].
The plant tends to be slightly invasive[] with new stems emerging at some distance from the parent plant[]. It can become a noxious weed among cereal crops[].

Known Hazards

Although no specific records of toxicity have been found for this species, the seed and other parts of many Lathyrus species contain a toxic amino acid. It is produced in the plant at about the same time that the seed starts to develop. In small quantities the amino acid is innocuous, and the seeds of several Lathyrus species are eaten as a nutritious part of the diet. However, in larger quantities (the seed should form less than 30% of a balanced diet), it can cause a very serious disease of the nervous system known as 'lathyrism'. Symptoms appear as a paralysis of the muscles below the knees, pains in the back, followed by weakness and stiffness of the legs and progressive locomotive incoordination[, , ].

Botanical References

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Range

Eurasia - western Russia to Spain, east through Russia to the Russian Far East, through Turkey and the Caucasus to central Asia and western China

Habitat

Cornfields and hedgerows, avoiding acid soils[]. Water meadows, riverbanks; at elevations from 500 - 2,400 metres in western China

Properties

Weed Potential	Yes
Edibility Rating
Habit	Perennial Climber
Height	1.20 m
Pollinators	Bees
Cultivation Status	Wild

Cultivation Details

Lathyrus tuberosus is a moderately cold-hardy plant, able to tolerate temperatures down to around -20°c when fully dormant[].
An easily grown plant, succeeding in any moderately good garden soil[]. It prefers a limestone soil in a warm position[], and likes some shade[].
The earthnut pea has occasionally been cultivated for its edible root[, ].
Slugs are inordinately fond of this plant and will totally destroy it given a chance[].
A good bee 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[].

Edible Uses

Root - cooked or raw[, , , , ]. Sweet and starchy, it is delicious when baked with a flavour that is somewhat like a sweet potato[, ]. Taste trials consistently place this root very highly, it is certainly one of our favourites[]. Unfortunately, yields are rather low and so the plant is only worthwhile growing as a taste treat, not as a staple crop[].

Medicinal

None known

Other Uses

None known

Propagation

Pre-soak the seed for 24 hours in warm water and then sow in early spring in a cold frame[]. When they are large enough to handle, prick the seedlings out into individual pots and plant them out in the summer.
If you have sufficient seed, then it can also be sown in situ in mid spring[].
Division of the tubers when the plant is dormant in spring or autumn.