Herbs, annual, 30-80 cm tall. Stem erect, few branched or unbranched, green when young, dark with age, puberulous. Petiole puberulous; leaf blade ovate to broadly ovate, 5-10 × 3-5 cm, membranous, appressed hirsute, base cordate to truncate and decurrent on petiole, margin crenate-toothed, apex acute; secondary veins 3 or 4 on each side of midvein. Inflorescences bisexual, cymose, ca. 5 mm wide. Male flowers: calyx lobes ca. 1 mm; stamens exserted. Female flowers: ovary ± depressed globose; style filiform, 1-1.5 mm, 2 × as long as ovary. Achenes ovoid, 3-angled, ca. 1 mm. Fl. May-Aug.
Herbs , to ca. 8 dm. Stems erect, branched, pubescent with hooked trichomes. Leaves: stipules linear to linear-lanceolate, 1.8-2.5 mm; petiole 1-6 cm, often ± as long as leaf blade. Leaf blade to 2.5-10 × 1-7 cm, papery, base cordate to truncate, margins crenate-dentate, apex acute to acuminate; surfaces abaxially and adaxially appressed-hirsute. Inflorescences cymes, dense, 4-8 mm wide, subtended by narrow bract; peduncle 1-2 cm. Flowers light green, staminate and pistillate in same cyme. Staminate flowers: calyx campanulate; stamens exserted. Pistillate flowers: calyx boat-shaped; ovary globose, puberulent, somewhat depressed in axis; style reddish purple, filiform. Achenes white, oval, 3-angled, ca. 1 mm, minutely muricate, with 2 triangular, membranous appendages. Seeds explosively expelled.