Description from Flora of China
Justicia paniculata N. L. Burman, Fl. Indica, 9. 1768.
Herbs to 50 cm tall, annual, much branched. Stems 4-angled, glabrous. Petiole 0.3-1 cm; leaf blade ovate-lanceolate, lanceolate, or narrowly elliptic, 1.5-7 × 1-2.5 cm, both surfaces glabrous, abaxially pale green, adaxially green, secondary veins 3-5 on each side of midvein, base attenuate and decurrent onto petiole, margin entire, apex acute to shortly acuminate. Inflorescences terminal, leafy panicles of secund racemes; rachis glabrous to sparsely pubescent; bracts triangular to subulate, 1-1.5 mm; bracteoles linear to subulate, 1-1.5 mm. Pedicel 2-9 mm, sparsely pubescent with gland-tipped and non-glandular trichomes (gland-tipped pubescent). Calyx 2.5-3 mm, outside glabrous or gland-tipped pubescent, lobes subulate. Corolla white, 0.9-1.5 cm, outside gland-tipped pubescent; tube basally funnelform for 4-8 mm; lower lip with purple dots, 5-7 mm, erect, lobes ca. 3 mm; upper lip 5-7 mm, reflexed, 2-lobed, lobes ca. 1 mm. Stamens exserted from corolla tube. Style 6-10 mm, sparsely pilose toward base. Capsule ellipsoid-compressed, 1.5-2 × 0.3-0.4 cm, glabrous or sparsely pubescent with gland-tipped trichomes, ca. 12-seeded. Seeds ca. 2 × 1.5 mm, rugose. Fl. and fr. throughout year. 2n = 50.
This species is used medicinally.
Cultivated or naturalized in Anhui, Fujian, Guangdong, Guangxi, Hainan, Hubei, Hunan, Jiangsu, Jiangxi, Yunnan, and Zhejiang [native to India and Sri Lanka; cultivated or naturalized in Cambodia, Indonesia, Laos, Malaysia, Myanmar, Thailand, Vietnam, and Caribbean].