Polygonum lanatum Roxb., Fl. Ind. 2: 285. 1832; Polygonum lanigerum auct. non R. Br.: Meisn., Monogr. Polygonum 70. 1826. p.p.; Hook.f., Fl. Brit. Ind. 1: 35. 1886; R.R.Stewart, Ann. Cat. Vasc. Pl. W. Pak. & Kashm. 206. 1972; Polygonum lapathifolium var. lanatum (Roxb.) Steward in Contr. Gray Herb. 88: 46. 1930; Persicaria lapathifolia subsp. lanata (Roxb.) Sojak in Preslia 65: 154. 1974; Persicaria lapathifolia var. lanata (Roxb.) Hara in Hara et al., Enum. Fl. Pl. Nepal 3: 176. 1982.

Erect to suberect, annual, 60-150 cm tall; stem simple or branched, usually reddish especially at nodes covered with white cottony tomentum. Leaves shortly petioled, up to 3 mm long, lamina lanceolate to elliptic lanceolate, 5-15 x 0.8-2.5 cm, acute to acuminate, lanate on both surfaces but more on the under surface. Ochreae tubular, sometimes completely covering the internodes, ± lanate, margins eciliate. Inflorescence a branched raceme 2.5-5 (-6) cm long; peduncles eglandular, sometimes lanate. Ochreolae subtubular, ovate, sparsely lanate. Flowers white, c. 2.5 mm long, shortly pedicelled. Tepals 4, rarely five, red or white. Stamens 6, filaments filiform, ± equal to the style. Ovary biconcave, styles 2, stigmas 2, capitate. Nut c. 2 x 1.8-2 mm, biconcave, flat, black and shining.

Fl. Per. April-September.

Type: Near Calcutta, Icones no. 939 (K!) (vide Sealy Kew Bull. 1956: 372. 1956).

Grows in ditches and near ponds from plains to 1500 m; Distribution: Pakistan, India extending to Malaysia through Myanmar.

Very close to Persicaria lapathifolia in having eciliate ochrea and general habit but differs by eglandular peduncles and leaves covered with white, cottony tomentum on both sides, while in P. lapathifolia the peduncles are scurffy glandular and the leaves are without canescence above or on both sides.