Herbs , annual, with taproot, 1.5-8 dm. Stems usually branched from base, erect or reclining. Leaf blades narrowly ovate to orbiculate, distal blades sometimes lanceolate, 2-8 × 1-6 cm, base nearly cordate to rounded, sometimes cuneate in distal leaves, margins serrate, apex rounded to acute; cystoliths rounded or ± elongate. Inflorescences ± globose cymes. Flowers unisexual, staminate and pistillate intermixed in same inflorescence, sessile to short-pedunculate. Pistillate flowers: outer tepals linear, 0.4-0.8 mm, inner tepals ovate, 1.4-2 × 1-1.4 mm. Achenes ovoid to broadly ellipsoid, 1.2-1.4(-1.6) × 0.8-1 mm. 2 n = 26. Flowering all year except early winter. Rich, wooded slopes, bluffs, stream banks, swamps, waste places, and fields, often on limestone or nearly neutral soils; 0-600 m; Ala., Ark., Fla., Ga., Ill., Kans., Ky., La., Miss., Mo., N.C., Ohio, Okla., S.C., Tenn., Tex.; n Mexico.
Fibrous-rooted or weakly taprooted annual, 3-8 cm, branched from the base, subglabrous except for a few stinging hairs; stipules oblong, 1-3 mm; lvs crenate-serrate, the lower broadly ovate to subrotund, the upper progressively narrower and smaller; fl-clusters subglobose to short-spicate, shorter than the petioles; achenes ovate, 1-1.5 mm, less than 1 mm wide. Moist woods and thickets; W.Va., s. O., and Ky. to Mo. and Okla., s. to Ala. and Mex. Spring and summer.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.