Herbs annual, less often subshrubs, villous or pubescent, rarely glabrous. Stem erect or oblique, usually much branched. Leaves alternate, sessile or subsessile, terete, semiterete, or narrowly complanate, margin entire. Flowers axillary, sessile, usually 1-3-glomerulate, bisexual, sometimes some female, without bractlets. Perianth subglobose, 5-parted, herbaceous, usually hairy; segments incurved, abaxially with transverse, winglike, membranous, veined appendages in fruit. Disk absent. Stamens 5, inserted at base of perianth; filaments flattened; anthers broadly oblong, exserted. Ovary broadly ovoid; ovule subsessile; style obscure; stigmas 2 or 3, filiform, papillose. Utricle depressed globose; pericarp membranous, not adnate to seed. Seed horizontal, globose or ovoid, depressed, slightly emarginate near hilum; testa membranous, glabrous; embryo slender, annular; perisperm not copious.
Herbs and subshrubs, annual or perennial, glabrous or densely tomentose-sericeous. Stems erect, ascending, or prostrate, simple or branched, not jointed, not armed, not fleshy; branches alternate [proximal sometimes almost opposite]. Leaves alternate [rarely proximal almost opposite], sessile (sometimes narrowed into pseudopetiole); blade obovate-lanceolate, lanceolate, linear, or filiform, flat or semiterete, base truncate, margins entire, apex rounded. Inflorescences terminal, spicate or paniculately branched; flowers solitary or in 2-5-flowered clusters in axils of bracts; bracts leaflike. Flowers bisexual or pistillate, sessile; perianth segments 5, with horizontal, membranous wing [sometimes reduced to slightly winged tubercles] adaxially; stamens 5; stigmas 2-3. Fruiting structures: perianth covering utricles at maturity, utricles compressed-spheric or compressed-elliptic; pericarp free or nearly so, membranous. Seeds wedge-shaped; seed coat dull brown, slightly ribbed; embryo annular; perisperm copious. x = 9.
"Fls perfect or pistillate; cal minute, subglobose, 5-lobed; stamens 5, exsert; ovary depressed, styles 2–3, elongate, filiform; cal at maturity enclosing the fr, each sep bearing a horizontal wing; pericarp thin, free; seed horizontal, flat; embryo annular; annual or perennial herbs or shrubs with narrow lvs and small fls sessile in the axils of bracts, forming dense, axillary or terminal spikes. 30+, mainly Old World."
|[For W. D. J. Koch, 1771-1849, German naturalist and physician]|