THE SORREL FAMILY (Polygonaceae)

The name refers to the many swollen nodes the stems of most species possess. It is derived from Greek; poly means many and goni means knee or joint. The family is present worldwide, but is most diverse in the North Temperate Zone. Several species are cultivated as ornamentals. A few species provide lumber, the fruit of the sea grape (Coccoloba uvifera) is eaten, and in Florida, jelly is made from it and sold commercially. The seeds of two species known as buckwheat (sarrasin in French) provide grain (its dark flour is known as blé noir (black wheat), the leaf stems (petioles) of rhubarb are used as food and the leaves of the common sorrel (Rumex acetosa) are eaten in salads or as a potherb. Polygonaceae also includes some of the worst weeds, including species such as Japanese knotweed which are notoriously difficult to eradicate.

Leaves are usually simple and arranged alternately along the stem and often a distinct sheath encloses the point at which the leaf stems (petiole) joins the stem. Flowers of sorrel or dock varieties are often single-sexed, small, lacking colour and individually inconspicuous although the clusters may be large and highly visible. These flowers are wind pollinated and in the fruiting stage the colour of the winged seed cases may become deeply red-brown. In buckwheat on the other hand the small flowers have pink petals, both male and female parts and are insect pollinated.

Source: Wikipedia)