Description from Flora of China
Verbena jamaicensis Linnaeus, Sp. Pl. 1: 19. 1753.
Subshrubs or robust perennial herbs, 0.6-2 m tall. Branches 4-angled when young, sparsely pubescent to subglabrous. Petiole winged; leaf blade elliptic to oblong-ovate, 2.4-8 X 4.5 cm, papery, subglabrous, base elongated, margin serrate, apex acuminate, veins 5 or 6 pairs. Spikes few to 20 cm or longer; bracts ca. 5 mm, membranous. Calyx ca. 6 mm, glabrous. Corolla dark blue; tube 7-12 mm, slightly curved. Capsules included in calyx.
Shaded grassy places in valleys; 300-600 m. Naturalized weed in Fujian, Guangdong, Guangxi, Hainan, Taiwan, Yunnan [tropical America, naturalized throughout tropics].