Polygonum posumbu Buch.-Ham. ex D. Don, Fl. Nep. 71. 1825; Hook. f., Fl. Brit. Ind. 5: 38. 1886; R. R. Stewart, Ann. Cat. Vasc. Pl. W. Pak. & Kashm. 211. 1972; Bhopal & Chaudhri in Pak. Syst. 1(2): 78. 1977 (p.p.); P. caespitosum Blume, Bijdr. 532. 1826; P. donii var. tenerum Meisn. in Wall. Pl. As. Rar. 3: 58. 1832. p.p.

A very slender, perennial herb, usually creeping below with ascending branches, branches glabrous, 25-30 (-40) cm high. Leaves petiolate, petiole strigosely hairy, up to 5 mm long, 2-12.5 x 0.5-1.8 cm, elliptic to elliptic-lanceolate, entire, with acute base and caudate to acuminate apex, midrib, undersurface and margins glabrous to sparsely, strigosely hairy. Ochreae tubular, sparingly strigose, 0.5-1.0 cm long, ciliate at the mouth, cilia stiff equalling or slightly longer than the tube. Inflorescence a very slender, interrupted, few flowered, filiform, terminal or axillary, 3-10 cm long raceme on almost equally long peduncle, ochreolae interrupted, 0.3-0.4 mm long, lax, tubular, ciliate at the mouth, cilia shorter than ochreolae. Flowers white or pink, subsessile. Tepals 5, biseriate, c. 2.5 mm long, outer two ± boat shaped, inner three flat, oblong, obtuse, eglandular. Stamens 5-6 (-8), equal, filaments long, anthers basifixed. Ovary trigonous with 3 styles, styles free most of their length, fused at the base; stigmas capitate. Nut trigonous, 2.0-2.5 x 1-1.5 mm, black, shining.

Fl. Per.: May-October.

Type: Hab. in Nepalia, Buchanan-Hamilton.

Not very common in our area. Grows on damp and shady areas between 1000-3000 m. It resembles superficially with a more common species viz., Persicaria longiseta but the spikes are more slender and longer in P. posumbu and the leaf bases are acute; Distribution: Himalayas - Kashmir to Bhutan, Asam, Bangla Desh, extending upto Malaysia.