Urticaceae

Urticaceae, the nettle family, is a family of flowering plants in the order Rosales. It comprises several dozen genera and several hundred species, with a cosmopolitan distribution in temperate and tropical regions. Members range from herbaceous perennials to climbers and shrubs, and they occupy a variety of habitats from disturbed ground to forest understories.

Most species have opposite leaves with serrated margins and produce stinging hairs on leaves and stems; these trichomes can inject irritants such as histamine and formic acid when brushed. Not all genera share this trait, however; for example, Parietaria lacks stinging hairs. Flowers are small and inconspicuous, usually arranged in dense inflorescences such as spikes or panicles. They are typically unisexual or dioecious, and wind pollination is common. The fruits are small, dry, and typically one-seeded.

Ecology and uses: The best-known member is Urtica dioica, the stinging nettle, valued as a leafy vegetable, medicinal herb, and traditional source of fiber. Ramie, from Boehmeria nivea, provides a high-strength textile fiber. Several genera, including Pilea and Parietaria, are common in disturbed habitats and are grown as ornamentals in some regions.

Taxonomy: Urticaceae is placed in the Rosales order, with molecular studies clarifying relationships to Moraceae and Cannabaceae in some classifications. The name derives from the Latin urtica, nettle, reflecting the familiar stinging genera within the family.