Description from Flora of China
Poinsettia pulcherrima (Willdenow ex Klotzsch) Graham.
Shrubs to small trees, 1-3(-4) m, many branched. Stems glabrous. Leaves alternate; stipules minute, membranous, caducous; petiole 2-5 cm, glabrous; leaf blade ovate-elliptic, oblong, or lanceolate, often shallowly lobed, 6-25 × 4-10 cm, abaxially pubescent, adaxially shortly pubescent or glabrous, base attenuate, apex acuminate or acute. Cyathia in a very congested, 1-sided synflorescence, subtended by 5-7 petiolate leaflike bracts, these narrowly elliptic, 3-7 × 1-2 cm, usually entire, sometimes repand-lobed, scarlet, peduncle 3-4 mm; involucre urceolate, light green, 7-9 × 6-8 mm, lobes 5, lacerate, triangular, glabrous; glands usually 1, rarely 2, yellow, compressed, 2-lipped, 4-5 × ca. 3 mm. Male flowers many, usually exserted from involucre; bracts linear, pilose. Female flower: ovary glabrous, pedicellate, exserted from involucre, smooth; styles connate below middle; stigma deeply 2-lobed. Capsule, 3-lobed-globose, 1.5-2 × ca. 1.5 cm, smooth and glabrous. Seeds ovoid, ca. 10 × 8-9 mm, gray or light gray, subsmooth, without caruncle. Fl. and fr. Oct-Apr.
Euphorbia pulcherrima is cultivated worldwide on a massive scale as a potted plant.
Widely cultivated and occasionally escaped and naturalized. Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hubei, Hunan, Jiangsu, Jiangxi, Shandong, Sichuan, Taiwan, Yunnan, Zhejiang; also cultivated in C and N China [native to Central America].