Impatiens cosmia J. D. Hooker; I. crassicornu J. D. Hooker.

Plants annual, 30-60 cm tall. Stem erect in upper part, prostrate basally, slender, glabrous; nodes slightly swollen, with adventitious roots. Leaves opposite, sessile or subsessile; leaf blade gray-green abaxially, green adaxially, linear or linear-lanceolate, rarely obovate, 2-10 × 0.5-1 cm, rigidly papery, with stipular basal glands, abaxially glabrous, adaxially scabrous, lateral veins 5-7 pairs, inconspicuous, base subcordate, truncate, or rounded, margin remotely spiniform-serrate, apex acute or slightly obtuse. Inflorescences 1-flowered, or flowers 2- or 3-fascicled in leaf axils; peduncles absent. Pedicels 2-4.4 cm, slender, often scabrous hairy on one side, bracteate at base; bracts linear. Flowers purple-red or white, large. Lateral sepals 2, linear, ca. 1 × 0.1 cm, apex acute. Lower sepal funnelform, ca. 1.5 cm deep, striate, gradually narrowed into an incurved or involute, slender spur. Upper petal orbicular, ca. 1 cm in diam., apex emarginate, mucronulate, abaxial midvein narrowly carinate; lateral united petals not clawed, 1.4-1.5 cm, 2-lobed; basal lobes suborbicular, small; distal lobes broadly obovate to dolabriform (axe-shaped), apex rounded-obtuse; auricle narrow. Stamens 5; filaments linear, compressed; anthers ovoid-orbicular, apex obtuse. Ovary fusiform. Capsule elliptic, turgid at middle, glabrous. Seeds black, globose, ca. 2 mm in diam., shiny. Fl. Jun-Aug, fr. Sep-Nov. 2n = 16.

The whole plant is used medicinally for relieving fever and pain, removing toxic materials, promoting blood circulation, treating diarrhea, curing urinary infections, and healing carbuncles.

Often beside ponds, streamsides, field margins, swamps; 100-1200 m. Anhui, Fujian, Guangdong, Guangxi, Hainan, Hunan, Jiangxi, Yunnan, Zhejiang [India, Malaysia, Myanmar, Thailand, Vietnam].