- Name also: Danzig Vetch
- Family: Pea Family – Fabaceae (Leguminosae)
- Growing form: Perennial herb. Rootstock quite thick, creeping, branched, woody.
- Height: 30–60 cm (12–25 in.). Stem ascending–erect, sparsely branched, bristly, soft-hairy.
- Flower: Corolla irregular (zygomorphic), reddish violet, 10–13 mm (0.4–0.52 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. Wings and keel light-coloured. Calyx 5-lobed, lobes different lengths, shorter than calyx tube. Stamens 10, filaments with fused bases. A single carpel. Inflorescence a long-stalked, 5–15-flowered raceme.
- Leaves: Alternate, short-stalked–stalkless, stipulate. Blade pinnate, 6–12 pairs, terminal leaflet modified into a tendril. Leaflets narrowly elliptic–lanceolate, with entire margins. Stipules small.
- Fruit: 15–30 mm (0.6–1.2 in.) long, glabrous, yellowish brown, unilocular, 1–3-seeded pod.
- Habitat: Forest margins, light forest margins, rocks.
- Flowering time: June.
- Endangerment: Endangered, protected in all of Finland, except the Åland Islands.
Our flora in Finland contains a whole group of species that are established in several or only one place in the southernmost parts of Finland, and this group includes Kashubian vetch, which is rare. It was discovered for the first time in 1936 from a hill in a stony field in Tenhola, and this is still the only known stand. Kashubian vetch’s Finnish stand is regarded as a legacy from the warmer period that followed the Ice Age, but the species could just as well have arrived in Finland with traffic. Its demands regarding climate and habitat mean that it could in principle thrive across a much larger area of southern Finland. It is quite common in southern Sweden and in its most northerly habitat it grows in hillside forests and semi-broad-leaved forests, which are populated by species that grow commonly in Finland. If a vetch is found in southern Finland which looks different from tufted vetch and black pea, and which has purplish red and white-flecked flowers and only 2 or 3-seeded pods, it could be Kashubian vetch, one of Finland’s rarest plants.