nettle

Any of a group of weedy plants with stinging hairs on oval, tooth-edged leaves; the hairs contain nerve poisons that penetrate the skin and cause a rash. The flowers are small and greenish, carried on spikes emerging at the same point where the leaves join the stem. The common nettle (U. dioica) grows on waste ground in Europe and North America, where it was introduced. (Genus Urtica, family Urticaceae.)