Ground Polygonum

Persicaria capitata is planted as a garden groundcover. It escapes infrequently in the flora area; once established outside of cultivation it can be difficult to eradicate.

Plants annual or perennial, 0.5-5 dm; roots also often arising from proximal nodes. Stems prostrate, glabrous or glandular-pubescent. Leaves: ocrea brown or reddish brown, cylindric to funnelform, 5-12 mm, chartaceous, base inflated or not, margins oblique, eciliate or ciliate with bristles to 1.5 mm, surface lanate, sometimes also glandular-pubescent; petiole 2-5 mm, winged distally; blade ovate to elliptic, 1.5-4(-6) × 0.6-2.5(-3.3) cm, base cuneate or tapering, margins ciliate with reddish, multicellular hairs, apex acute, faces glandular-pubescent abaxially and adaxially, not glandular-punctate. Inflorescences terminal, 5-20 × 7-18 mm; peduncle 10-40 mm, glabrous or stipitate-glandular in distal 5; ocreolae overlapping, margins eciliate. Pedicels spreading, 0.5-1 mm. Flowers 1-5 per ocreate fascicle; perianth greenish white proximally, pinkish distally, urceolate, glabrous, nonaccrescent; tepals 5, elliptic, 2-3 mm, apex acute to obtuse; stamens 8, filaments distinct, free; anthers pink to red, elliptic; styles 3, connate to middle or distally. Achenes included, reddish brown to brownish black, 3-gonous, 1.5-2.2 × 1-1.5 mm, shiny, smooth or minutely punctate.

Perennial herb, rootstock stout, with several branches from the rootstock, 15-25 cm long, trailing or creeping, usually rooting below. Leaves 1-3.5 (-4.0) x 0.75-2.5 cm, ovate, acute, base rounded or cuneate, pubescent-hairy, serrate-dentate, margin hairy, petiole 0.3-0.75 cm long. Ochrea 0.5-1.25 cm long, ovate, ciliate, hairy, tubular. Inflorescence a dense, capitate head, usually solitary, peduncle 1-4 cm long glandular-hispid or sometimes glabrous. Flowers 0.5-1.25 mm across, pink, pedicel very small, up to 1 mm long. Ochrealae 1.5-3.5 mm long, lanceolate, entire, acuminate. Tepals 5, parted nearly to the base, 1.5-2.0 x c. 1.0 mm, oblanceolate, obtuse, 3-veined, stamens 5-6, filaments long, equal, anthers dorsifixed. Ovary 0.50-1.0 x c. 0.5 mm, trigonous; styles three, long filiform, free about half the length with capitate and exserted stigmas. Nuts 1-2.0 x 0.5-0.75 mm, trigonous, dark brown, shining, glabrous, striate.

Himalaya (Punjab to NEFA), Tibet, Assam, east to W. China.

Distribution: Pakistan, India (Himalayas) extending in east up to W. China through Xizang.

introduced; Calif., La., Oreg.; Asia (Bhutan, w China, n India, Nepal); introduced also in the Pacific Islands (Hawaii).

600-2400 m

Fl. Per.: May-August.

Flowering Jun-Sep.

Disturbed, urban places; 0-500m.

A fairly uncommon plant, grows on moist rocks between the altitudes of 1200-2200 m.

Polygonum capitatum Buch.-Ham. ex D. Don, Prodr. Fl. Nep. 73. 1825; Hook. f., Fl. Brit. Ind. 1: 44. 1886; R.R.Stewart, Ann. Cat. Vasc. Pl. W. Pak. & Kashm. 204. 1972; Bhopal & Chaudhri in Pak. Syst. 1(2): 74. 1977.

Polygonum capitatum Buchanan-Hamilton ex D. Don, Prodr. Fl. Nepal., 73. 1825

capitata: in the form of a head, capitate

Vigorous trailing perennial.

Native of the Himalayas

Persicaria capitata, the pink-headed persicaria, pinkhead smartweed, pink knotweed, Japanese knotweed, or pink bubble persicaria, is an Asian species of plants in the genus Persicaria within the buckwheat family. It is native to Asia (China, Indian Subcontinent, Indochina) and grown as an ornamental in other countries. It has become naturalized in Australia, South Africa and a few scattered locations in the United States.