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dotted knotweed, dotted smartweed, renouée ponctuée, water smartweed

prickly smartweed

Habit Plants annual or perennial, 1.5–12 dm; roots also often arising from proximal nodes; rhizomes often present. Plants annual, 3–8 dm; roots not also arising from proximal nodes.
Stems

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

ascending to erect, ribbed or obscurely so, glabrous or glandular-pubescent distally;

prickles 1–1.5 mm.

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, 8–14 mm, chartaceous, base inflated or not, without prickles, margins truncate, ciliate with bristles 2–4 mm, surface with appressed bristles along veins;

petiole 0.5–1.5 cm;

blade lanceolate to narrowly elliptic, 5–12.5 × 1.5–3.5 cm, base acute, margins entire, antrorsely ciliate, apex acute acuminate, rarely obtuse, faces glabrous or pubescent and, usually, with antrorse prickles along midvein abaxially and adaxially.

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.

racemelike, uninterrupted or interrupted proximally, 20–45 × 5–10 mm;

peduncle 20–40 mm, usually stipitate-glandular at least proximally;

ocreolae usually overlapping, sometimes not overlapping proximally, 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.

2–4 per ocreate fascicle;

perianth pale green, often tinged red, glabrous, accrescent, not becoming blue and fleshy in fruit;

tepals 5, connate 1/4–1/3 their length, petaloid, elliptic to broadly elliptic, 3–4 mm, apex obtuse;

stamens 8, filaments distinct, free;

anthers pink, ovate;

styles 2, connate to middle.

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, black, biconvex, 2.5–3 × 2.3–2.8 mm, dull, rugose.

2n

= 44.

Persicaria punctata

Persicaria bungeana

Phenology Flowering Jun–Nov. Flowering Jul–Sep.
Habitat Shallow water, shores, marshes, floodplain forests Cultivated fields
Elevation 0-1500 m (0-4900 ft) 300-400 m (1000-1300 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
IA; IL; MN; e Asia (n China, Japan, Korea, Manchuria) [Introduced in North America]
[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 bungeana is a weed of soybean fields (R. N. Andersen et al. 1985). It is not known how or when it was introduced into the midwestern United States.

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

Source FNA vol. 5, p. 586. FNA vol. 5, p. 578.
Parent taxa Polygonaceae > subfam. Polygonoideae > Persicaria > sect. Persicaria Polygonaceae > subfam. Polygonoideae > Persicaria > sect. Echinocaulon
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. 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. 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 bungeanum
Name authority (Elliott) Small: Fl. S.E. U.S., 379. (1903) (Turczaninow) Nakai: in T. Mori, Enum. Pl. Corea, 131. (1922)
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