Polygonales

(botany) An order of dicotyledonous plants in the subclass Caryophyllidae characterized by well-developed endosperm, a unilocular ovary, and often trimerous flowers.

An order of flowering plants, division Magnoliophyta (Angiospermae), in the subclass Caryophyllidae of the class Magnoliopsida (dicotyledons). The order consists only of the family Polygonaceae, with about 800 species, most abundant in north temperate regions. Within its subclass the order is characterized by its well-developed endosperm; an ovary with but one chamber(unilocular), mostly tricarpellate with a single basal ovule which is usually straight and has the micropyle at the opposite end from the stalk (orthotropous); the flowers are often trimerous, that is, with floral parts in sets of three, and usually two or three sets of stamens. Rhubarb (Rheum rhaponticum) and buckwheat (Fagopyrum esculentum) are familiar members of the Polygonales. See also Buckwheat; Caryophyllidae; Magnoliopsida; Rhubarb.