polygonaceae

Polygonaceae, commonly known as the knotweed or smartweed family, is a family of flowering plants in the order Caryophyllales. The family comprises about 60 genera and more than 1,200 species. Members are primarily herbaceous plants, though a few tropical genera include shrubs or small trees. They are distributed worldwide, with greatest diversity in temperate regions and mountainous areas.

A hallmark of Polygonaceae is the ochrea, a papery sheath formed by fused stipules at the nodes that encircles the stem. Leaves are simple, alternate, and often with entire margins. Flowers are small and frequently arranged in dense inflorescences such as spikes, racemes, or panicles; they may be bisexual or unisexual. The perianth usually consists of four to six tepals, and the ovary is superior. The fruit is typically a small achene.

The family includes many familiar genera, such as Rumex (docks), Persicaria and Polygonum sensu lato (knotweeds and smartweeds), Fallopia and Reynoutria (knotweed genera), Fagopyrum (buckwheat), Rheum (rhubarb), Oxyria, and Bistorta. In modern classifications, Polygonum sensu lato has been split, and Persicaria, Fallopia, and Reynoutria are treated as distinct genera.

Economically, Polygonaceae provides crops such as buckwheat and rhubarb, while several species are invasive or weedy, notably Japanese knotweed and certain docks. The group also includes ornamentals and plants adapted to a wide range of habitats from wetlands to dry soils.