Adapted from Flora of North America, treatment by Jess A. Peirson (description and habitat information based on U.S.A. collections only):

Annual herbs, from spreading taproots. Stems erect or ascending, branched; glabrous to sparsely pilose, or puberulent, 20--100 cm. Leaves alternate; bracteate leaves few, in a tight, involucrate whorl subtending the inflorescence, similar in size and shape to distal stem leaves, red, pink, or white at the base (or distal-most bracts completely colored); stipules absent or minute, glanduliform; petiole 2--20 mm, glabrous to pilose, or often barbellate abaxially near the blade junction; blade 15--250 x 4--40 mm, linear, lanceolate, elliptic, or narrowly to broadly pandurate and unequally 4-lobed, penninerved, midvein prominent, glabrous to sparsely puberulent adaxially, sparsely pilose to subglabrous abaxially, base acute to cuneate, apex acute to cuneate, margin subulately glandular-serrulate distally, or sparsely glandular and subentire, hirtellous to nearly glabrous, flat to revolute. Cyathia 5--75 per inflorescence; peduncle 1.6--2.8 mm. Involucre campanulate (occasionally broadly so), 1.8--2.8 x 2.2--2.8 mm, glabrous; involucral lobes triangularly 3--5 lobed; glands usually solitary, sessile to sub-stipitate and narrowly to broadly attached, 1--1.4 x 0.9--1.6 mm, opening oblong, yellow-green. Staminate flowers 7--20. Pistillate flower: ovary glabrous, style 1.6 mm, divided nearly to the base. Capsule depressed-spheroid to ellipsoid, 3-lobed, 2.8--3.2 x 4--4.5 mm, glabrous, columella 2--2.7 mm. Seeds cylindric to ovoid, bluntly apiculate, rotund, 2.3--3.1 x 1.9--2.5 mm wide, black to ashy gray or light brown, uniformly tuberculate (the tubercles arranged in a median, transverse ridge in cylindric seeds); caruncles obsolete.

Flowering and fruiting late spring to fall.
Bottomland forests, stream and river banks, bases of bluffs, and also fallow fields, roadsides, and open disturbed areas; 0--1800 m.

This species is native to the midwestern and southeastern United States, south through Mexico and the West Indies to northern South America. The tetraploid form of the species has been widely cultivated. Naturalized tetraploid populations occur throughout warmer areas of the species' native range into South America and throughout warmer areas of the Old World.

Leaf shape can be polymorphic in this species but not to the extent as in Euphorbia heterophylla.