Herbs, green to yellowish or reddish, 5–15(–25) dm, glabrous. Stems erect, mostly branched. Leaves mostly opposite or mostly alternate; petiole 0.3–4+ cm; blade green on both sides, ovate or ovate-lanceolate to cordate-hastate at base, 15–180 × 8–135 mm, margin entire or more rarely irregularly toothed or lobed, apex attenuate to acuminate or rounded. Inflorescences of spikes disposed in leafless panicles. Staminate flowers 5-merous. Pistillate flowers dimorphic, some ebracteolate and with 5-parted perianth, others without perianth enclosed by a pair of sessile or very shortly stipitate bracteoles. Fruiting bracteoles samaralike, orbicular to oval or ovate, compressed, 5–18 mm, united only at base, entire, faces smooth. Seeds of ebracteate flowers black, horizontal, convex, 1–2 mm wide, lustrous; those of bracteolate flowers olivaceous brown, vertical, flat, 3–4.5 mm wide, dull. 2n = 18.
