Lathyrus sativus aka Indian Pea

Lathyrus sativus is an annual climber in the pea family, Fabaceae. Common names include grass pea, chickling pea, and Indian pea. Kew links its cultivated origin to the Balkan Peninsula. Its true wild origin remains unclear. Plants found among crops may be remnants of past planting. People have grown this food crop for thousands of years.

The plant branches freely and climbs with tendrils. Garden plants reach about 3–5 feet [1–1.5 metres] high. They spread up to 1.6 feet [0.5 metres]. Other accounts describe shorter plants, with extremes reaching 5.6 feet [1.7 metres]. The stems have angles and thin wings. Each mid-green leaf has two narrow, pointed leaflets. A long, thin taproot anchors the plant. Single flowers open in late spring and early summer. Most are blue, with pink and white on the upper petal. Some plants bear pink or white blooms. Seedpods follow the flowers.

Grow grass pea in full sun with moist, well-drained soil. It accepts sand, loam, clay, and chalk. Acid, neutral, and alkaline soils all suit it. Give the stems support, or let them climb nearby shrubs. The RHS assigns it hardiness rating H6 under UK conditions. Soak seed for a day before spring sowing. Autumn or winter sowing under cover is another option. Plants need no pruning. Removing spent blooms before seeds form can extend flowering.

Grass pea suits borders, containers, banks, and informal gardens. It can also cover supports beside walls or screens. Root bacteria help it fix nitrogen from the air. Growers use it as green manure to enrich soil. Its broad root system also helps hold soil against erosion. Disease problems are uncommon, according to the RHS. Aphids, thrips, slugs, and snails may still cause damage.

People eat the seeds, young pods, and young shoots after preparation. However, this is not a crop to treat as harmless. It contains ODAP, a toxic amino acid, throughout the plant. Heavy, repeated intake can cause lathyrism, a serious nerve disease. The damage can be lasting and can impair muscle control. Soaking and boiling lower toxin levels but do not establish universal safety. Changing the water can improve toxin removal. Grinding seeds into flour may leave the toxin behind. The RHS also warns that eating the plant can cause harm. Seed oil has a recorded use as a strong laxative. That use is dangerous, not a safe home remedy.