Polygonaceae

Abstract

Annual or perennial herbs, shrubs, trees, or clambering, climbing, or twining lianas. Stems often sulcate, geniculate, or striate and occasionally hollow, sometimes swollen at the nodes. Leaves mostly alternate and penninerved, seldom opposite or whorled, simple, margins usually entire, petiolate to sessile; stipules commonly well developed and connate into a tubular, persistent or deciduous, usually membranous to hyaline, often bilobed or fringed sheath, the ocrea, or sometimes much reduced or wanting. Inflorescences axillary or terminal, simple or branched thyrsi, either on main stems or on lateral shoots, panicle-, raceme-, or spike-like in appearance, but basically compounded of partial inflorescences, which are cluster-like dichasia or helicoid cymes; partial inflorescences subtended by bracts; each flower subtended by a persistent membranous, tubular ocreola consisting of the fused bracteoles; partial inflorescences rarely subtended by, and partly included in an involucre (subfam. Eriogonoideae). Flowers relatively small, bi- or unisexual, pedicellate, articulate to the pedicel, often with a distinctly stipitate base above the articulation; perianth regular, segments 2–6, basally connate into a minute to conspicuous floral tube, green or colored, commonly in 2 similar to slightly dissimilar whorls of 3 segments, sometimes in one whorl of 5, mostly persistent in fruit; stamens (2−)6–9, rarely more; filaments free or basally connate, often basally adnate to the perianth tube forming a distinct ring; an annular nectary disk often present around the base of the ovary, or the nectaries several and placed between the bases of the stamens, anthers tetrasporangiate and dithecal, usually versatile and introrse, opening by longitudinal slits; gynoecium of (2−)3(−4) carpels united to form a compound, unilocular, superior ovary; styles 1–3, distinct or proximally united, the stigmas filiform, peltate, or capitate, entire or variously fringed; ovule single on a basal or very shortly columnar free-central placenta, orthotropus or rarely anatropous.