A vetch is a climbing plant in the pea and bean family. It has thin stems, small leaves in pairs along the stem, curly threads (tendrils) at the tip that grab onto other plants so it can climb, and small flowers — usually purple, pink, or white. After the flowers, it makes little pods with seeds inside, just like a tiny pea pod. Farmers grow it mostly as food for cows, horses, and sheep, either fresh in the field or cut and dried into hay. They also plant it to make the soil better: plants in this family put nitrogen (a kind of natural fertiliser) back into the ground, so a farmer may grow vetch in a field for one season and then plough it in before planting something else. Some kinds grow wild along roads and in grass, and people just call those wild vetch. This is a farming and countryside word, not a city one. Most English speakers who did not grow up near farms know the word only vaguely — they might picture 'some purple wildflower' — and many have never said it out loud. You will meet it in books about the countryside, in gardening writing, and in plant names like 'crown vetch' and 'hairy vetch'. It is nearly always a plant word; there is no verb.

野豌豆（蠶豆屬/巢菜屬的豆科植物，常種來當牧草或綠肥）