5. Aconogonon tortuosum (D. Don) Hara in Fl. E. Himal. 632. 1966; in Hara et al., Enum. Fl. Pl. Nepal 3: 172. 1982; Grierson & D.G.Long, Fl. Bhutan 1: 156. 1983; S.-P. Hong in Act. Univ. Upsal. (Symb. Bot. Upsal.) 30(2): 90. 1992.
Polygonum tortuosum D. Don, Prodr. Fl. Nep. 71. 1825; Hook. f., Fl. Brit. Ind. 5: 52. 1886; Rech.f. & Schiman-Czeika in Rech.f., Fl. Iran. 56: 53. 1968; R.R.Stewart, Ann. Cat. Vasc. Pl. W. Pak. & Kashm. 209. 1972; Pleuropteropyrum tortuosum (D. Don) Munshi & Javeid, Polygon. Kashm. Himal. 80. 1986.
Erect, 30-150 cm high, branched, pubescent to hairy, perennial subshrub with ± elongated rhizome. Stem ± terete, profusely, dichotomously branched from base or above, pubescent to hairy or glabrous, woody. Leaves (1-) 1.5-4 (-6.8) x (0.9-) 1.0-3 (-3.5) cm, elliptic, lanceolate-ovate, acute, or obtuse at the apex, margin entire or undulate, ciliate or scabrous or glabrous; glabrous or pubescent on both sides with slightly rough or coriaceous texture, petiole 0.5-4.0 mm long. Ochrea 5.0-15 mm long, ovate-broadly ovate, entire to dentate, tubular, truncate, hairy. Inflorescence many flowered, dense, pubescent, up to 2.0 cm long pedunculate, terminal or axillary panicles; panicles (0.8-) 1.5-5 (-7) cm long. Flowers 2-3.5 mm across, pedicel 1-2.5 mm long, slightly longer in fruit. Ochreolae 1.5-3 mm long, lanceolate, cartilaginous, ciliate, hairy. Tepals 5, creamy white, subequal,1.5-3.5 x 0.75-1.25 mm, ovate to ovate elliptic, obtuse, entire, parallel veined, veins 3. Stamens 8, subexserted, filaments long, equal. Ovary 0.5-1.5 x c. 1.0 mm, oblanceolate, trigonous with three short styles and capitate stigma. Nuts (2-) 2.5-4 x 1.5-1.9 mm, ovate, brown, shining, included or slightly exserted from the tepals.
Two varieties are recognized in our region.