- Name also: Cow Vetch, Boreal Vetch, Bird Vetch (USA)
- Family: Pea Family – Fabaceae (Leguminosae)
- Growing form: Perennial herb. Rootstock thin. With subterraneous runners.
- Height: 20–100 cm (8–40 in.). Stem limp, climbing, branched, bristly, glabrous–short-haired.
- Flower: Corolla zygomorphic, blue–bluish violet, 8–12 mm (0.32–0.48 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, lowest lobe same length as calyx-tube. A single carpel. Stamens 10, filaments with fused bases. Inflorescence a long-stalked, dense, 10–30-flowered raceme.
- Leaves: Alternate, short-stalked–stalkless, stipulate. Blade pinnate, 6–12-pairs, terminal leaflet modified into a tendril. Leaflets narrowly ovate–linear, with entire margins. Stipules 2-lobed.
- Fruit: 10–25 mm (0.4–1 in.) long, flattish, glabrous, brown, 1-parted, 4–8-seeded pod (legume).
- Habitat: Meadows, roadsides, banks, waste ground, shores, forest margins, herbaceous forests.
- Flowering time: June–August.
Tufted vetch is one of Finland’s better-known Pea family plants, and one of the most common meadow species. As a native it grew on Finnish sea-shores at least, and possibly along the banks of waterways. The coastal form often stands out from its relatives that grow close to people as it is more densely haired and has brighter coloured flowers.
Tufted vetch’s limp stem climbs towards the light by leaning and supporting itself on other vegetation. On top of the leaves are tendrils, mid-ribbed prehensile organs, which support the stem. When they sense a solid surface, growth stops at the point of contact and accelerates on the other side, so the tendril curves and eventually curls around the object and the plant continues climbing in this fashion towards the light. Its climbing skills mean it doesn’t have to use nutrition and energy to grow a thick stem. Tufted vetch is also supported by its subterraneous runners, which anchor the plant into the soil over a wide area. The result is a green tangle, from which violet racemes emerge. They are exceptionally noticeable: most vetches have 2–5 flowers in a group, but tufted vetch’s racemes have up to 40. The species’ pod is as distinctive as its flower. It contains spherical, tough-skinned seeds, whose small size has given the plant the Finnish name “mouse’s pea”. The seeds don’t make much of a meal, and in fact they shouldn’t even be tasted because they are mildly poisonous.
Tufted vetch is a perennial plant which is poisonous to a certain degree. Its stems are limp, bristly, branched and climbing. Its runners grow close to the ground and their roots can go quite deep (around 30 cm (12 in.)) into the soil. This partly explains why the plant thrives on different kinds of soil, from alkaline to acidic peat. In an agricultural context it thrives best in different kinds of meadows and fallow land, grain fields and among root crops.