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.

Persicaria chinensis (synonym Polygonum chinense), commonly known as creeping smartweed or Chinese knotweed, is a plant species from the family Polygonaceae. It is widespread across China, Japan, the Indian Subcontinent, Indonesia, Malaysia, and Vietnam. It is a common plant in Malaysia and Vietnam, where it is used in herbal remedies, such as for the treatment of dysentery, enteritis, and sore throat. It is a weed in some coastal areas of New South Wales and Queensland in Australia.

Persicaria chinensis is a perennial climber that grows to 2–3 m high. Its stems are glabrous and red-brown, with longitudinal stripes. Its leaves have oval blades, are 4–8 cm long and 3–5 cm wide, with pointed apex and round or nearly cordate base. Its cymes emerge at terminals, and are 5–7 cm long, with small white or pink flowers. Its fruits are berries, globose in shape and enclosed in the enlarged and fleshy calyx at maturity. They are edible and sour tasting. The seeds are small and black.