Polygonaceae

Abstract

The Polygonaceae, known informally as the knotweed Family or smartweed, namely, buckwheat Family, in the Order of Caryophyllales, is a Family of dicotyledonous flowering plants, consisting of about 48 genera with more than 1200 species, worldwide distributed, mostly in N temperate regions. Plants are usually herbaceous, shrubs, or small trees. Stems are erect, twining or prostrate, striate, grooved, or prickly, and nodes often inflated. Leaves are simple, usually alternate, and petiolate or subsessile. Stipules are often united to a membranous sheath surrounding nodes. Flowers are small, actinomorphic, usually bisexual, rarely unisexual, and sometimes plants monoecious or dioecious. Inflorescence is terminal or axillary, usually arranged to spicate, capitate, and racemose or paniculate. Pedicel is occasionally articulate. Perianths are 3–6 partite, petaloid, imbricate or 2-whorled, persistent, and sometimes with inner sepals enlarged or with appendages. Stamens are usually 8, rarely 6–9 or less, disk annular, or absent. Ovary is superior, 1-loculed, containing 1 erect, basal ovule. Styles are 2–3, free, or connate below. Fruit is an achene, ovoid, trigonous, lenticular, and sometimes with wings. Seeds are with copiously powdery endosperm. Embryo is often curved, somewhat lateral, and cotyledon flat. Twenty species, belonging to four genera, mostly in Polygonum Linn. Genus, are illustrated in this chapter.