Rha—Russian name for the River Volga, near which rhubarb was first found. Rha—also ancient Greek name for rhubarb.
Perennial herbs with thick, woody rhizomes. Leaves mostly basal, large, often lobed. Ocreas persistent. Flowers bisexual in branching clusters. Perianth segments 6, free. Stamens 9. Stigmas 3. Fruit a nut with 3 wings.
Division or seed.
Medicinal and as a vegetable.
About 50 species from E Europe, temperate and subtropical Asia.
Source: (1997). Polygonaceae. In: . Horticultural Flora of South-eastern Australia. Volume 2. Flowering plants. Dicotyledons. Part 1. The identification of garden and cultivated plants. University of New South Wales Press.