Polygonum longisetum De Bruyn in Miq., Pl. Jungh. 307. 1854; Polygonum serrulatum auct. non Lag. 1817 sensu Hook.f., Fl. Brit. Ind. 1: 38. 1886; R. R. Stewart, Ann. Cat. Vasc. Pl. W. Pak. & Kashm. 212. 1972; Polygonum caespitosum Bl. var. longisetum (De Bruyn) Danser, Polyg. Nied. 170. 1927; Persicaria caespitosa var. longiseta (De Bruyn) C. F. Reed in Phytologia 63 (5): 410. 1987.

Ascending-erect, 15-60 cm high, glabrous, branched from base or above, annual herb. Stem brownish or reddish brown, glabrous, canaliculate. Leaves 2.5-12 x 0.75-3.5 cm, lanceolate-elliptic, acuminate, hairy, entire, with a rounded or cordate base, petiole 2-7 mm long. Ochrea 8-20 mm long, ovate, tubular, setose or ciliate, cilia almost equalling the ochreae or longer. Inflorescence very laxly flowered, interrupted 0.8-4.0 cm long, terminal-axillary raceme. Flowers up to 2.0 mm across, pedicel 1.0 mm long. Ochreolae 1.0-3.0 mm long, setose or ciliate, cilia 1.0-4.0 mm long. Tepals 5, biseriate, unequal, red, pink or whitish, ovate-obovate, obtuse. Stamens 5-8, filaments long. Ovary trigonous, rounded, with 3 styles, styles free above, fused below. Nuts trigonous, shining, black.

Fl. Per.: May-August.

Type: Insulam Javae in monte Gedé, altitude. 3-5000 ft, ubi flor. legit mens. December-Febr. (Junghuhn.).

A fairly common species from plains to 2500 m, grows in ditches, moist places. Often confused with Persicaria salicifolia (Brous. ex Willd.). See discussion under excluded species; Distribution: Kashmir to Nepal, extending upto Japan through N. Myanmar and China.