Description from Flora of China
Plants to 1 m tall. Stems pale gray, puberulent to glabrous. Leaves opposite; petiole to 1 cm; leaf blade lanceolate or oblong-lanceolate, 6-15 × 1-4 cm, glabrous or abaxially puberulent along veins, base decurrent into petiole, apex acuminate or acute. Cymes up to as long as leaves, 10-20-flowered; peduncle 3.5-6 cm, pubescent. Pedicel 1.2-2.5 cm, pubescent. Sepals lanceolate, ca. 3 × 1 mm, pubescent. Corolla purple or red, 7-9 mm; lobes oblong, 5-8 × ca. 3 mm, reflexed. Corona lobes yellow or orange, 3.5-4 mm; gynostegium 2.5-3 mm. Follicles fusiform, 5-10 × 1-1.5 cm. Seeds ovate, 6-7 × ca. 3 mm; coma 2-4 cm. Fl. almost all year. 2n = 22.
Cultivated and naturalized in Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hubei, Hunan, Jiangsu, Jiangxi, Qinghai, Sichuan, Taiwan, Xizang, Yunnan, Zhejiang [native of tropical America, widely introduced elsewhere]