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dotted knotweed, dotted smartweed, renouée ponctuée, water smartweed

Asian knotweed, petite renouée, pygmy smartweed, small smartweed, small water-pepper

Habit Plants annual or perennial, 1.5–12 dm; roots also often arising from proximal nodes; rhizomes often present. Plants annual, 0.5–3(–4) dm; roots also sometimes at from proximal nodes; rhizomes and stolons absent.
Stems

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

decumbent or ascending, branched proximally, scarcely ribbed, glabrous or scabrous distally.

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, 3–10 mm, chartaceous, base not inflated, margins truncate, ciliate with bristles (0.3–)1–3(–5) mm, surface glabrous or strigose, not glandular-punctate;

petiole 0.1–0.2 cm, glabrous or strigose, leaves sometimes sessile;

blade without dark triangular or lunate blotch adaxially, linear to linear-lanceolate, (1–)2–7.5(–10) × (0.2–)0.4–1(–2.3) cm, base tapered to cuneate, margins antrorsely scabrous, apex acute to acuminate, faces glabrous or sparingly strigose, especially along midveins, not glandular-punctate.

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 and axillary, ascending to erect, usually interrupted proximally, uninterrupted distally, 10–50 × 2–4 mm;

peduncle (0–)2–25 mm, sometimes absent on axillary inflorescences and flowers thus enclosed in ocreae, glabrous;

ocreolae not overlapping proximally, usually overlapping distally, margins ciliate with bristles (0.1–)0.6–2(–2.7) mm.

Pedicels

ascending, 1–4 mm.

ascending, 0.5–1 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(–4) per ocreate fascicle, homostylous;

perianth roseate to red, rarely white, glabrous, not glandular-punctate, scarcely accrescent;

tepals 5, connate ca. 1/3 their length, obovate to elliptic, 2.5–3 mm, veins not prominent, not anchor-shaped, margins entire, apex obtuse to rounded;

stamens 5(–6), included;

anthers yellow to pink, elliptic;

styles 2(–3), connate at bases.

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, brownish black to black, biconvex or, rarely, 3-gonous, (1.5–)1.8–2.3(– 2.7) × (1.1–)1.3–1.5(–1.8) mm, shiny, smooth.

2n

= 44.

Persicaria punctata

Persicaria minor

Phenology Flowering Jun–Nov. Flowering Jul–Oct.
Habitat Shallow water, shores, marshes, floodplain forests Damp, open 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
CT; IN; LA; MA; NE; PA; VA; VT; NB; ON; QC; Europe [Introduced in North America]
[WildflowerSearch map]
[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.)

Persicaria minor is synonymized with P. maculosa in most North American floras; its distribution in the flora area is poorly known. Hybrids between P. minor and P. maculosa have been documented in Europe (R. H. Roberts 1977).

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

Source FNA vol. 5, p. 586. FNA vol. 5, p. 593.
Parent taxa Polygonaceae > subfam. Polygonoideae > Persicaria > sect. Persicaria Polygonaceae > subfam. Polygonoideae > Persicaria > sect. Persicaria
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. chinensis, P. glabra, P. hirsuta, P. hydropiper, P. hydropiperoides, P. lapathifolia, P. longiseta, P. maculosa, P. meisneriana, 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 minus, Polygonum minus var. subcontinuum
Name authority (Elliott) Small: Fl. S.E. U.S., 379. (1903) (Hudson) Opiz: Seznam, 72. (1852)
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