Polygoneae
A very distinct natural order of herbs, shrubs, or sometimes trees, broadly dispersed; the arborescent species are nearly all tropical American, the shrubs are mostly limited to the Eastern Mediterranean or Western Asiatic region, and the herbaceous kinds affect temperate and mountainous regions. Flowers hermaphrodite, or, in a few genera, unisexual, regular, usually rather small springing from the axils of leaves or bracts (sometimes ochreiform), solitary or fasciculate, in racemes or spikes; perianth inferior, calycine or coloured, with four to six lobes or segments; stamens six to nine, rarely fewer, or many and indefinite; filaments filiform or dilated at base, free or connate in a ring at the base; anthers, two-celled, often versatile; ovary trigonal or compressed, sessile or shortly adnate ovary trigonal or compressed, sessile or shortly adnate to the perianth at the base; pedicels frequently articulated. Fruit a nut, trigonal, compressed, or rarely quadrigonal, rarely naked, usually covered by the perianth. Leaves alternate or rarely opposite, variable in form, rarely lobed or divided; petioles usually more or less dilated and stem-clasping. One of the most important products of the order is Rhubarb (Rheum officinale). Buckwheat, Sorrels, and Docks may be mentioned as other economic members of the order. Polygoneae comprises thirty genera and about 600 species. Examples are: Coccoloba, Fagopyrum, Muehlenbeckia, Polygonum, and Rheum.