Toothed Spurge

Herbs, annual, 20-50 cm tall, Root fibrous, 7-10 cm × 2-3 mm thick. Stems single, many branched above base, 2-5 mm thick, minutely pubescent and sparsely setose. Lower leaves opposite; stipules minute, caducous; petiole 0.3-2 cm, minutely puberulent; leaf blade linear to ovate, 2-7 × 0.5-2 cm, adaxial surface often with purplish spot, both surfaces coarsely pilose on veins or glabrous, base attenuate, margin entire, repand-toothed, or shallowly lobed, very variable, with narrow marginal vein, apex acute or obtuse. Inflorescence terminal, cyathia in whorl of 2 or 3 congested 1-sided cymes; lower involucral leaves 2 or 3, similar to normal leaves; primary rays 2-4 cm; upper involucral leaves few, reduced. Cyathium stipe 1-4 mm; involucre campanulate, ca. 3 × 2 mm, lobes 5, triangular, lacerate; gland 1, lateral on margin of cup, light yellow-brown, cup-shaped, ca. 1.2 mm in diam. Male flowers many, exserted from involucre; anthers yellow. Female flower: ovary globose, glabrous; styles free; style arms 2-lobed. Fruiting pedicel short, as long as cup; capsule compressed globose, ca. 4 × 4-5 mm, glabrous. Seed ovoid-globose, ca. 2 × 1.5-2 mm, gray to almost black, papillate-tuberculate, adaxially black grooved; caruncle small, peltate, yellow, sessile. Fl. and fr. Jul-Oct. 2n = 28*.

Naturalized recently in grasslands in the Beijing Botanical Garden [native to North America].

Euphorbia purpureomaculata T. J. Feng & J. X. Huang.

Euphorbia dentata is a species of spurge known by the common names toothed spurge and green poinsettia. It is native to parts of North and South America, and is present elsewhere on the continents. Its true native range is uncertain. It is a noxious weed in some areas. This is a hairy annual herb with an erect or somewhat erect stem reaching anywhere from 20 to 50 centimeters tall. Its hairy, pointed leaves are a few centimeters long, widely to narrowly lance-shaped, and generally toothed. The inflorescence appears at the end of branches and contain cream or yellowish staminate or pistillate flowers just a few millimeters wide. The fruit is a lobed spherical or heart-shaped capsule about half a centimeter wide which contains three bumpy rounded seeds.