Chinese Knotweed

Plants perennial, 7-10 dm; roots not also arising from proximal nodes; rhizomes present. Stems ascending to erect, sometimes scandent, glabrous or retrorsely hispid. Leaves: ocrea brownish, cylindric, 15-25(-50) mm, coriaceous proximally, chartaceous distally, base often inflated, margins oblique, eciliate, surface glabrous or pubescent; petiole 1-2.5 cm, winged at least distally; blade lanceolate to ovate or elliptic, 4-16 × 1.5-8 cm, base truncate to broadly cordate, margins glabrous or antrorsely scabrous with whitish hairs, apex acuminate, faces glabrous or hispid abaxially and adaxially, sometimes pubescent only along veins abaxially, not glandular-punctate but often minutely reddish-punctate abaxially. Inflorescences terminal or terminal and axillary, 3-6 × 3-6 mm; peduncle 10-30 mm, stipitate-glandular along entire length; ocreolae overlapping, margins eciliate. Pedicels mostly ascending, 2-3 mm. Flowers 1-3 per ocreate fascicle; perianth white to pink, campanulate, glabrous, accrescent; tepals 5, ovate, 3-4 mm, apex acute to obtuse; stamens 8, filaments distinct, free; anthers red or purple, elliptic; styles 3, connate proximally. Achenes included in fleshy, bluish black perianth, black, 3-gonous, 2.8-4 × 2-3 mm, dull, minutely punctuate.

Erect-suberect, up to 1 m tall, divaricately branched shrubby perennial. Stem ± woody, circular, glabrous or sparsely pubescent or glandular pubescent. Leaves 6-17 x 1-7.5 cm, ovate oblong, linear or deltoid ovate, base usually truncate, apex acute or acuminate, entire, petiole 4-9 mm long usually 2-auricled at the base. Ochrea 6-15 (-20) mm long, foliaceous, orbicular, dentate, ± tubular.

Inflorescence a compound corymb, peduncles glandular hairy. Flowers 2.0-3.5 mm across, pedicel c. 1 mm long, ochreolae, ovate, hairy, eglandular, eciliate, tepals 5, 2.5-4 x 1.25-1.5 mm, lanceolate, acute, entire, white or pinkish, accrescent and fleshy. Stamens 7-8, filaments long, filiform, equal, attached to the staminal tube, ovary 1-1.5 x 0.5-0.75 mm, trigonous with 3 filiform styles, free above the middle, connate below, stigmas capitate. Fruits baccate, fleshy, fruiting perianth c. 2 mm thick, fleshy. Nuts trigonous 2-3 (-4) x 1.5-2 mm, included in the fleshy perianth.

Distribution: India, Bhutan, Myanmar, China, Japan, Philippines, Sri Lanka, introduced in Pakistan.

Fl. Per.: September-November.

Polygonum chinense Linnaeus, Sp. Pl. 1: 363. 1753

Polygonum chinense L., Sp. Pl.: 363. 1753; Meisn. in DC. Prodr. 14: 130. 1857; Hook.f., Fl. Bri. Ind. 5: 44. 1886; R.N.Parker, For. Fl. Punj. Haz. 423. 1921 (reprint. ed.); Bhopal & Chaudhri in Pak. Syst. 1(2): 74. 1977; Ampelygonum chinense (L.) Lindley in Bot. Reg. 24. 63. 1838.