Description from Flora of China
Justicia pectinata Linnaeus, Amoen. Acad. 4: 299. 1760; Rungia parviflora Nees subsp. pectinata (Linnaeus) L. H. Cramer; R. parviflora var. pectinata (Linnaeus) C. B. Clarke; R. pectinata var. clarkeana Handel-Mazzetti.
Herbs 20-50 cm tall, annual or perennial. Stem basally prostrate and rooting at nodes then erect, minutely pubescent. Petiole 0-7 mm; leaf blade oblong-elliptic, 1-4 × 0.4-1.4 cm, glabrous except for a few trichomes along veins, secondary veins ca. 4 on each side of midvein, base cuneate and decurrent onto petiole, margin entire, apex acute. Spikes axillary or terminal, 0.5-2 cm, 1-sided, solitary or sometimes 2 or 3 compound; bracts dimorphic; sterile bracts green, elliptic, ca. 4 × 0.7 mm, glabrous, apex acute; fertile bracts circular to obovate, 4-5 × ca. 2 mm, pubescent, margin broadly hyaline, apex obtuse to rounded to emarginate and mucronulate; bracteoles elliptic, 2-3 mm, margin ciliate, apex 2-cleft and subacute. Calyx colorless, pubescent; lobes linear-lanceolate, ca. 3 × 0.5 mm, margin narrowly hyaline, apex mucronulate. Corolla blue or white, ca. 5 mm, outside pubescent; lower lip 3-lobed, lobes triangular; upper lip ovate, 1-2 mm, apex emarginate. Staminal filaments glabrous. Ovary glabrous. Capsule ellipsoid, ca. 2.5 mm, glabrous, 2-4-seeded, apex apiculate. Seeds orbicular in outline, ca. 1 mm in diam., minutely verrucose. Fl. Nov-Jan, fr. Jan-Apr. 2n = 26, 52.
Rungia pectinata is a common weed in disturbed habitats.
This species is used medicinally.
Wastelands. Guangdong, Guangxi, Hainan, Yunnan [Bangladesh, Bhutan, India, Laos, Myanmar, Nepal, Sri Lanka, Thailand, Vietnam].