This description is based on Mayfield (1997).
"Trees or spreading shrubs, 10 m tall. Roots diffusely taprooted. Stems solitary, to 8 cm thick at the base; branches alternate, divaricate, and ascending, with light gray and warty to lustrous and bronze-colored bark, the growing shoots usually glabrous, less often puberulent. Leaves alternate above the epicotyledonary node; petioles 5-12 cm long, glabrous to puberulent; blades 10-25 cm long, 5-15 wide, broadly elliptic, to pandurate with four shallow, rounded lobes, the bases obtuse to subtruncate, terminating at the petiole junction, with a pair of dark-brown secretory patches flanking the petiole, the apices broadly acute to obtuse, with a broadly rounded tip; upper surfaces glabrate to very sparsely puberulent, glabrous and lustrous-ciliate along the margins; lower surfaces sparsely puberulent; margins entire. Umbels 3-rayed, dense, spreading, flattopped; principal umbel leaves numerous, scattered throughout the umbels, radiating and involucrate, narrowly oblong to elliptic, acuminately tapered to the apex, scarlet pale red below, rarely greenish-white throughout. Cyathia broadly cupulate, 6-8 mm tall, 5-7 mm wide, glabrous; glands solitary, yellow with red at the apex, ca. 4.5 mm tall, ca. 5 mm wide, the attachment broadly sessile, the opening oblong; involucral lobes rounded, divided into numerous linear lobules. Staminate flowers 25-30 per fascicle. Pistillate flower pedicel elongating to ca. 10-12 mm; ovaries glabrous, green with red along the center; style branches ca. 8-10 mm long, deeply bifurcate, the lobes recoiled. Capsules broadly oblong, green tinged with red to yellowish-brown. Seeds cylindriform, apiculate, rotund, 8-9 mm tall, ca. 6-7 mm wide, ca. 6-7 mm thick; surface gray to fuscous, completely smooth; caruncles obsolete; caruncular facet obsolete, or slightly flattened."

Dry forest. Also in disturbed sites along rivers, roads, steep mountain slopes, forest gaps and ecotones.

The species is most closely related to Euphorbia cornastra (Yang et al. 2012).

Northern Guerrero Province in Mexico has been found to be the ancestral area of E. pulcherrima (cultivated poinsettia) (Trejo et al. 2012). See also www.explorelifeonearth.org/poinsettia.html

Ornamental. Widely cultivated and commercialized as potted plant.

Euphorbia pulcherrima has apparently escaped widely in the tropics, having become a problem pest at least in parts of Africa, India, and the Canary Islands (Mayfield, 1997).