- Name also: Tare, Garden Vetch, Spring Vetch, Narrw-leaved Vetch
- Family: Pea Family – Fabaceae (Leguminosae)
- Growing form: Annual herb.
- Height: 15–70 cm (6–30 in.). Stem limp–ascending–erect, hairy.
- Flower: Corolla zygomorphic, purple–red, 10–30 mm (0.4–1.2 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, filaments with fused bases. A single carpel. Inflorescence a stalkless, 1–2-flowered raceme.
- Leaves: Alternate, short-stalked–stalkless, stipulate. Blade pinnate, 1–7 pairs, terminal leaflet modified into a tendril. Leaflets obovate–lanceolate–linear, sharp-pointed, sometimes with notched tip, with entire margins. Stipules with toothed margins, dark-spotted.
- Fruit: 25–70 mm (1–2.8 in.) long, hairy–glabrous, yellowish brown–black pod (legume) sometimes narrower between seeds.
- Habitat: Fields, fallow land, wasteland, banks, roadsides, yards, meadows, harbours, railway yards. Also grows among fodder and green manure crops.
- Flowering time: June–August.
Genus Vicia’s name has been associated with vetch plants since ancient times. It was used for the first time by the Roman Marcus Varro in his agriculture text book, apparently referring to vetch. The name is based on the Latin verb vincere, ‘to twist’, and refers to the genus’s tendrils which twist around its own leaves and help the plant climb above other vegetation. Common vetch was brought to Finland as winter fodder for cattle, and the species spread to the wild to fallow fields as well as the forecourts round threshing places and mills. Like many old cultivated plants it is difficult to put one’s finger on common vetch’s origin, but presumably it is native to the Mediterranean countries. Vetches spread with the help of animals as well as people: the hard-shelled seeds survive digestive tracts unscathed and can spread a long way. Common vetch also has an ally in some of the smallest members of the animal kingdom. A close look reveals that its stipules have small black spots: these are nectaries, which tempt ants to the plant through the sweet fluid they emit. They defend the plant from pests and even bigger predators, and are rewarded with nectar.
There are three subspecies of common vetch in Finland: very rare narrow-leaved vetch (ssp. nigra) whose leaflets are narrowly elliptic, and ssp. sativa, which has obovate leaflets and largest flowers, and ssp. segetalis which is tallest of them all. Common vetch resembles bush vetch (V. sepium), which is clearly more common in Finland and which has wider, tipless leaflets.