Common Name: Beach Pea

General Information

Lathyrus japonicus is a herbaceous perennial plant that can grow up to 90cm tall; the stems often attatch themselves to the surrounding vegetation by means of tendrils[].
The plant is sometimes harvested from the wild for local use as a food, and also for use as an ingredient in cosmetic preparations..

Known Hazards

All parts of the plant, but especially the seed, 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

,

Range

Eurasia - Iceland, Norway to Britain, east to Russian Far East, n. China, Japan, Korea; northern N. America south to California, Illinois, New Jersey

Habitat

Sandy coasts from Alaska to N. California[].

Properties

Edibility Rating
Other Uses Rating
Habit	Perennial
Height	0.60 m
Pollinators	Bees, Lepidoptera
Cultivation Status	Wild

Cultivation Details

Lathyrus japonicus is a very cold-hardy plant, able to tolerate temperatures down to around -35°c when fully dormant[].
An easily grown plant, succeeding in any moderately good garden soil[]. It prefers a deep moist well-drained soil in a cool position[]. Prefers a position in full sun, growing well on hot sunny banks[].
The seed remains viable for 4 - 5 years in sea water[].
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

Young plant - raw or cooked. An excellent sustenance[].

Medicinal

None known

Other Uses

An extract of the whole plant is used as an ingredient in commercial cosmetic preparations as a skin conditioner[].

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 in spring. It may not transplant well so care should be taken[].