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Himalayan smartweed, Japanese knotweed, pink bubble persicaria, pink-head knotweed, pink-head persicaria, pinkhead smartweed

Habit Plants annual or perennial, 0.5–5 dm; roots also often arising from proximal nodes.

prostrate, glabrous or glandular-pubescent.

prostrate or decumbent to ascending or erect, branched, unarmed.


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.

ocrea usually chartaceous, rarely coriaceous proximally and chartaceous distally, margins eciliate or ciliate;

petiole usually winged, auriculate;

blade usually with dark triangular or lunate blotch adaxially, broadly elliptic to ovate, base cordate, rounded, truncate, or cuneate, margins entire.


terminal, 5–20 × 7-18 mm;

peduncle 10–40 mm, glabrous or stipitate-glandular in distal 1/5;

ocreolae overlapping, margins eciliate.

terminal or terminal and axillary, capitate, uninterrupted.


spreading, 0.5–1 mm.


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.

homostylous, articulation swollen or not;

perianth urceolate or campanulate;

tepals (4–)5, connate 1/3–1/2 their length;

stamens (5–)8;

styles deciduous, 2–3, included, spreading.


included, reddish brown to brownish black, 3-gonous, 1.5–2.2 × 1–1.5 mm, shiny, smooth or minutely punctate.

Persicaria capitata

Persicaria sect. Cephalophilon

Phenology Flowering Jun–Sep.
Habitat Disturbed, urban places
Elevation 0-500 m (0-1600 ft)
from FNA
CA; LA; OR; Asia (Bhutan, w China, n India, Nepal) [Introduced in North America; introduced also in the Pacific Islands (Hawaii)]
[WildflowerSearch map]
[BONAP county map]
Asia [Introduced in North America; introduced also in Europe, Africa, Pacific Islands]

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.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Species ca. 16 (3 in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

1. Achenes biconvex; abaxial surface of leaf blades glandular-punctate
P. nepalensis
1. Achenes 3-gonous; abaxial surface of leaf blades not glandular-punctate
→ 2
2. Leaf blade margins ciliate with reddish, multicellular hairs; ocreae lanate; peduncles glabrous or stipitate-glandular distally
P. capitata
2. Leaf blade margins glabrous or antrorsely scabrous with whitish hairs; ocreae glabrous or pubescent; peduncles stipitate-glandular along entire length
P. chinensis
Source FNA vol. 5, p. 579. FNA vol. 5, p. 579.
Parent taxa Polygonaceae > subfam. Polygonoideae > Persicaria > sect. Cephalophilon Polygonaceae > subfam. Polygonoideae > Persicaria
Sibling taxa
P. amphibia, P. arifolia, P. bicornis, P. bungeana, P. careyi, P. chinensis, P. glabra, P. hirsuta, P. hydropiper, P. hydropiperoides, P. lapathifolia, P. longiseta, P. maculosa, P. meisneriana, P. minor, P. nepalensis, P. orientalis, P. pensylvanica, P. perfoliata, P. punctata, P. robustior, P. sagittata, P. setacea, P. virginiana, P. wallichii
Subordinate taxa
P. capitata, P. chinensis, P. nepalensis
Synonyms Polygonum capitatum Polygonum section Cephalophilon
Name authority (Buchanan-Hamilton ex D. Don) H. Gross: Bot. Jahrb. Syst. 49: 277. (1913) (Meisner) H. Gross: Bull. Acad. Int. Géogr. Bot. 4: 27. (1913)
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