Urticaceae, or the nettle family, is a family of flowering plants. The family name comes from the genus Urtica (nettles). Urticaceae includes a number of well-known, interesting and useful plants, including genus Urtica (nettles), Boehmeria nivea (ramie), Pipturus albidus (mamaki), and Debregeasia saeneb (ajlai).
The family counts more or less 2600 species, grouped into 54 to 79 genera, according to the database of the Royal Botanic Gardens, Kew. The largest genera are Pilea (500 to 715 species), Elatostema (300 species), Urtica (80 species), and Cecropia (75 species).
Urticaceae can be found worldwide, apart from the polar regions.
APG II system puts Urticaceae in order Rosales, while older system consider it part of Urticales, along with Ulmaceae, Moraceae and Cannabaceae. APG still considers "old" Urticales a monophyletic group, but does not recognise it as an order on its own.
Urticaceae can be shrubs (e.g. Pilea), lianas, herbs (e.g. Urtica. Parietaria), or, rarely, trees (e.g. Dendrocnide, Cecropia).
Urticaceae have usually unisexual flowers and can be both monoecious or dioecious. They are pollinated by the wind. Most disperse their pollen when the stamens are mature and their filaments straighten explosively: a peculiar and conspicuously specialised mechanism.