Herbs annuals or perennial, shrubs, undershrubs or small trees, monoecious or rarely dioecious. Indumentum of simple hairs or glands, very rarely of stellate hairs.
Leaves alternate, undivided, generally petiolate, stipulate; stipules paired at the leaf base; stipels rarely present at apex of petiole or leaf base, caduceus; leaf blades entire or more commonly dentate or crenate-serrate, pinnately or palmately veined.
Inflorescences terminal or axillary, frequently both, unisexual or androgynous, generally solitary. Male inflorescences spicate, densely flowered, with several flowers at each node subtended by a minute bract. Female inflorescences generally spicate, sometimes racemose or panicle-shaped, with 1–3(–5) flowers at each node, usually subtended by a large bract, increasing and foliaceous in the fruit, generally dentate or lobed; sometimes subtended by a small bract, entire or lobed, non accrescent in the fruit. Androgynous inflorescences usually with female flowers at proximal nodes and male flower at distal nodes.
Flowers unisexual, apetalous, disc absent. Male flowers very small, shortly pedicellate, globose in bud; calyx parted into 4 small valvate sepals; stamens 4–8(–16) on a slightly raised receptacle, filaments free or basally connated; anthers with divaricate or pendulous thecae, unilocular, more or less elongated and later becoming vermiform; pollen grains oblate-spheroidal, with 3–5 pseudopores, tectate, psilate; pistillode absent. Female flowers generally sessile or subsessile, pedicellate in a few species; calyx of 3– (4–5) small sepals imbricate, connate at base; ovary of [1–2]3 carpels, surface often muricate, pubescent or papillose; ovules solitary in each cell, anatropes; styles reddish, free or basally connate, several times divided into filiform segment, rarely bifid or entire; staminodes absent.
Fruits capsular, small, 3-lobed, soon dehiscing septicidally into 3 bivalved cocci; generally surrounded by the accrescent female bract. Seeds small, ovoid or ellipsoid, usually carunculate, smooth or foveolate; endosperm present, whitish; the embryo straight; cotyledons broad and flat.
Allomorphic female flowers present in some species, generally terminal (sometimes median or basal) in the inflorescences; ebracteate, long pedicellate or subsessile; calyx as in the normal female flowers; ovary and fruits 1-2 locular.
José María Cardiel, Elena Dorda, Pablo Muñoz & Manuel Pardo de Santayana
Dpto. de Biología (Unidad de Botánica), Facultad de Ciencias. UAM
Ciudad Universitaria de Cantoblanco. 28049 Madrid. España