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dotted knotweed, dotted smartweed, renouée ponctuée, water smartweed

Chinese knotweed, Chinese smartweed

Habit Plants annual or perennial, 1.5–12 dm; roots also often arising from proximal nodes; rhizomes often present. Plants perennial, 7–10 dm; roots not also arising from proximal nodes; rhizomes present.
Stems

ascending to erect, branched, without noticeable ribs, glabrous, glandular-punctate.

ascending to erect, sometimes scandent, glabrous or retrorsely hispid.

Leaves

ocrea brown, cylindric, (4–)9–18 mm, chartaceous, base inflated, margins truncate, ciliate with bristles 2–11 mm, surface glabrous or strigose, glandular-punctate;

petiole 0.1–1 cm, glandular-punctate, leaves sometimes sessile;

blade without dark triangular or lunate blotch adaxially, lanceolate to lanceolate-ovate or subrhombic, 4–10(–15) × 0.6–2.4 cm, base tapered or cuneate, margins antrorsely strigose, apex acute to acuminate, faces glabrous or scabrous along midveins, glandular-punctate.

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

mostly terminal, sometimes also axillary, erect, interrupted, 50–200 × 4–8 mm;

peduncle 30–60 mm, glabrous, glandular-punctate;

ocreolae mostly not overlapping, margins mostly ciliate with bristles to 2 mm.

terminal or terminal and axillary, 3–6 × 3–6 mm;

peduncle 10–30 mm, stipitate-glandular along entire length;

ocreolae overlapping, margins eciliate.

Pedicels

ascending, 1–4 mm.

mostly ascending, 2–3 mm.

Flowers

2–6 per ocreate fascicle, homostylous;

perianth greenish proximally, white distally, rarely tinged pink, glandular-punctate with punctae ± uniformly distributed, scarcely accrescent;

tepals 5, connate ca. 1/3 their length, obovate, 3–3.5 mm, veins prominent or not, not anchor-shaped, margins entire, apex obtuse to rounded;

stamens 6–8, included;

anthers pink or red, elliptic to ovate;

styles 2–3, connate proximally.

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 or apex exserted, brownish black, usually 3-gonous, rarely biconvex, (1.8–)2.2–3.2 × 1.5–2.2 mm, shiny, smooth.

included in fleshy, bluish black perianth, black, 3-gonous, 2.8–4 × 2–3 mm, dull, minutely punctuate.

2n

= 44.

Persicaria punctata

Persicaria chinensis

Phenology Flowering Jun–Nov. Flowering Jul–Oct.
Habitat Shallow water, shores, marshes, floodplain forests Disturbed places
Elevation 0-1500 m (0-4900 ft) 0–100 m (0–300 ft)
Distribution
from FNA
AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; VA; VT; WA; WI; WV; WY; HI; BC; MB; NB; NS; ON; PE; QC; SK; Mexico; West Indies (Puerto Rico); Central America (Guatemala); South America (Brazil)
[WildflowerSearch map]
[BONAP county map]
from FNA
MA; MD; NJ; Asia [Introduced in North America; introduced also in the Pacific Islands (Hawaii)]
[BONAP county map]
Discussion

N. C. Fassett (1949) proposed a complicated classification for Persicaria punctata with 12 varieties in North America and South America. He also identified numerous specimens that he considered to be morphologically intermediate between various varieties. M. Dalci (1972) documented a wide range of phenotypic and genotypic variation throughout the range of P. punctata and extensive overlap in many of the features used by Fassett to distinguish varieties. Consequently, recognition of varieties does not seem warranted. Persicaria punctata and its close relatives P. robustior and P. glabra are unique among native North American smartweeds in possessing complex glands called valvate chambers in their epidermises. Persicaria punctata is confused most frequently with P. hydropiper; the achenes are diagnostic.

The Chippewa, Houma, and Iroquois prepared decoctions from leaves, flowers, and roots for use as analgesics as well as gastrointestinal, orthopedic, and psychological aids (D. E. Moerman 1998).

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

Varieties of Persicaria chinensis have been distinguished on the basis of stem pubescence, leaf shape, and leaf size. Whether those taxa merit recognition in the flora area is uncertain.

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

Source FNA vol. 5, p. 586. FNA vol. 5, p. 580.
Parent taxa Polygonaceae > subfam. Polygonoideae > Persicaria > sect. Persicaria Polygonaceae > subfam. Polygonoideae > Persicaria > sect. Cephalophilon
Sibling taxa
P. amphibia, P. arifolia, P. bicornis, P. bungeana, P. capitata, 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. robustior, P. sagittata, P. setacea, P. virginiana, P. wallichii
P. amphibia, P. arifolia, P. bicornis, P. bungeana, P. capitata, P. careyi, 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
Synonyms Polygonum punctatum, Polygonum acre var. leptostachyum, Polygonum punctatum var. confertiflorum, Polygonum punctatum var. ellipticum, Polygonum punctatum var. leptostachyum, Polygonum punctatum var. parviflorum, Polygonum punctatum var. parvum Polygonum chinense
Name authority (Elliott) Small: Fl. S.E. U.S., 379. (1903) (Linnaeus) H. Gross: Bot. Jahrb. Syst. 49: 269. (1913)
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