- Name also: Earthnut Pea, Aardaker, Tuberous Sweetpea
- Family: Pea Family – Fabaceae (Leguminosae)
- Growing form: Perennial herb. Rootstock with nut-sized tubers.
- Height: 30–80 cm (12–32 in.). Stem limp, sometimes climbing, bristly, wingless, glabrous.
- Flower: Corolla zygomorphic, rose red, 12–20 mm (0.48–0.8 in.) long. Petals 5; the upstanding the ‘standard’, the lateral two the ‘wings’, the lower two united to form the ‘keel’, overall shape of corolla being butterfly-like. Calyx 5-lobed. Stamens 10. A single carpel. Inflorescence long-stalked, 2–7-flowered raceme, flowers with strong fragrance.
- Leaves: Alternate, stalked, stipulate. Stalk wingless. Blade pinnate, 1 pair, terminal leaflet modified into a tendril. Leaflets elliptic–lanceolate, blunt, with entire margins, bluish green. Stipules narrow.
- Fruit: 20–40 mm (0.8–1.6 in.) long, flat, brown, 3–6-seeded pod (legume).
- Habitat: Rich forests, hedgerow, roadside embankments, railway yards, wasteland, parks. Ornamental, sometimes wild.
- Flowering time: July–August.
Tuberous pea grows ferally in most of Europe and western Asia. The species is an old food plant which has been cultivated since the 17th century. Tuberous pea grows a 3–5 cm (1.2–2 in.) long root tuber, which is both nutritional and good-tasting. The tubers are gathered in spring or autumn and eaten as they are, boiled or fried. As it gives a poor yield the species has been cultivated more as a delicacy than a real staple food.
Tuberous pea is grown in Finland mainly in the flower bed, although it is not a basic perennial. Sometimes its seeds or tubers jump the fence, in which case it grows with a limp stem close to the ground or competing amongst other vegetation. The species’ large, red, fragrant flowers, which also attract bees, are very attention-grabbing. Several other of the same kind of pea plant can also be spotted in Finnish flower beds, most notably perennial peavine (L. latifolius) and sweet pea (L. odoratus).