Duration: Annual
Nativity: Native
Lifeform: Forb/Herb
General: Erect annual 30-70 cm tall, beginning to branch ascendingly near base, stems light green, faintly striate, glabrous or essentially so.
Leaves: Opposite below, alternate from above first to third nodes to floral whorls, slender petioles .5-3 cm long, often gradually widening to cuneate base to leaf blade, latter ovate, obovate, elliptic, or lanceolate in outline 1-6 cm wide to 10 cm long, bright green above, pale to slightly glaucous beneath, margin entire or shallowly dentate and often lyrately lobed, lobes acutely to obtusely deltoid.
Flowers: Floral leaves similar to cauline ones, but some or all have white, pink, or scarlet near base; involucres clustered at tips of branches, 1.5-2 mm high, narrowly campanulate, green and glabrous, bearing a single unappendaged, discoid, sessile gland and deeply fimbriate-dentate lobes which slightly surpass gland.
Fruits: Capsules depressed-globose, strongly 3-lobed, 3.5-4.5 mm high, 5-6 mm in diameter, glabrous.
Ecology: Found on the margins of streams, washes, and hillsides from 2,500-5,000 ft (762-1524 m); flowers August-October.
Distribution: Cosmopolitan, especially at middle latitudes; Africa, Asia, Europe and Australia; southern half of the US; from s CA east to GA and FL; south through MEX to S. Amer.
Notes: Distinguished by being a mostly-hairless erect annual that can reach almost a meter in height; leaves are mostly alternate but can be variable in shape, from linear to lobed, but never dentate and are partially colored whitish at the base; the inflorescences do not have petaloid appendages (appear as if lacking petals); glands appearing as small cups; capsules strongly 3-lobed.
Ethnobotany: Unknown
Etymology: Euphorbia is named for Euphorbus, which derives from eu, good, and phorbe, meaning well-fed, while heterophylla means that the leaves are different on the same plant.
Synonyms: Euphorbia geniculata, Euphorbia prunifolia, Poinsettia geniculata, Poinsettia heterophylla
Editor: SBuckley 2010, FSCoburn 2015
