- Family: Pea Family – Fabaceae (Leguminosae)
- Growing form: Perennial herb. Rootstock long, many-branched.
- Height: 60–180 cm (25–70 in.). Stem limp, many-branched, climbing, bristly, glabrous.
- Flower: Corolla zygomorphic, white and bluish violet-veined, 12–18 mm (0.48–0.72 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, lobes short. Stamens 10, filaments with fused bases. A single carpel. Inflorescence a long-stalked, 6–18 flowered raceme.
- Leaves: Alternate, stalked, stipulate. Blade pinnate, 6–12-pairs, terminal leaflet modified into a tendril. Leaflets elliptic, with entire margins. Stipules narrowly lobed.
- Fruit: 25–30 mm (1–1.2 in.) long, glabrous, black, 4–5-seeded pod (legume).
- Habitat: Young forests, broad-leaved forests, forest margins, hedgerows, rocky outcrops, road banks.
- Flowering time: July–August.
Wood vetch is the biggest species in its genre, being capable of growing up to 2 metres (6.6 feet) high in favourable conditions. It is limp-stemmed, however, and unable to stay erect, so it supports itself on other vegetation, often trees, as it often grows in clearings or in the margins of semi-broad-leaved or broad-leaved forests. As it thrives in light-filled habitats it has been able to exploit as least considered logging and forest clearing. It favours soil which is not too acidic.
Wood vetch seems to require a lot of light, especially when it is flowering; it usually doesn’t flower in dense spruce forests, but is able to wait for a long time for sunshine to reach it. Its white flowers stand out from a distance in the semi-shade of the forest edge. Its upper petal, the standard, is erect, and is a very visible sign to insects. Its blue stripes point the way to the corolla throat and the nectar that is stored there for pollinators. Only heavy bumblebees and honeybees are able to pollinate wood vetch. The palmate keel, which is formed by the lower petals, conceals the stamens, pistil and nectar. It bends under the weight of a large insect, however, and the way into the flower is revealed. Small creatures can’t get at the nectar unless they break in by biting a hole in the calyx-tube. Wood vetch is regionally endangered.