This widespread, variable eastern weed was formerly misnamed maculata by F and others, due to confusion in nomenclature. In addition to several diagnostic differences from other Chamaesyce species in eastern North America (from leaves to seeds), nutans is usually a much larger plant, with ascending stems up to 8-10 dm long (versus mostly prostrate) and leaves 8-35 mm long (versus mostly 5-15 mm); plants are glabrous except for hairs up to 0.3 mm long on young stem surfaces; 2n = 12, 14, 22 (F, Cr, Y). Both nutans and maculata often have dark reddish/purplish "maculate" marks on leaves. During recent years, nutans has become locally abundant in dry summers after germinating on moist disturbed ground, including horticultural flower-beds, fescue pastures and hayfields after hard mowing (Rhodes & Phillips 2012; P. Adanick, pers. comm.). The genus Chamaesyce is sometimes combined within Euphorbia, but it remains sharply distinct in its narrow sense. Chamaesyce contains one of the largest concentrations of species with C4 photosynthesis among dicots (Ya & Berry 2011). In Kentucky, all are annuals, with germination generally delayed until daytime temperatures reach 25-30 deg, C.