Dotted Smartweed

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).

Plants annual or perennial, 1.5-12 dm; roots also often arising from proximal nodes; rhizomes often present. Stems ascending to erect, branched, without noticeable ribs, glabrous, glandular-punctate. 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. 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. Pedicels ascending, 1-4 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. 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. 2n = 44.

Erect, 20-40 cm high, simple-branched, glabrous to pubescent or less hairy, annual herb. Stem simple or branched, glabrous to pubescent or ciliate. Leaves 1.5-7 x 0.4-1.75 cm, lanceolate to elliptic, acute - acuminate, pubescent, hairy or ciliate, margin entire, ciliate, glandular-punctate mostly on the ventral side. Ochreae 0.75-1.75 cm long, ciliate or fimbriate, ciliae or fimbriae ± equal to ochrea. Inflorescence few flowered terminal or axillary racemes. Ochreolae 1.0-2.0 mm long, ciliate or fimbriate, ciliae or fimbriae ± equal to ochreolae. Flowers, subsessile on erect ± decurved, axillary or terminal filiform 3-5 (-7) cm long racemes. Tepals 5, biseriate, unequal pink, obovate-elliptic, obtuse, acute 1.5-2 x 1-1.25 mm. Stamens 8, flaments ± equal. Ovary trigonous, elliptic; styles 3, free or free up to half with capitate stigmas. Nuts trigonous, 0.75-1 (-1.25) x c. 0.5 mm, brown, shining.

B.C., Man., N.B., N.S., Ont., P.E.I., Que., Sask.; Ala., Ariz., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., Nebr., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Vt., Va., Wash., W.Va., Wis., Wyo.; Mexico; West Indies (Puerto Rico); Central America (Guatemala); South America (Brazil); Pacific Islands (Hawaii).

Distribution: North and South America, introduced elsewhere.

Flowering Jun-Nov.

Shallow water, shores, marshes, floodplain forests; 0-1500m.

Reported from N.W.F. province from Akbarpur, B. L. Burtt 1045, 1052 (E), by R. R. Stewart, l.c. but we have not come across any specimen from our area. Seems to be a rare species. Also reported by Munshi & Javeid l.c. from Benhama (Ganderbal) and Srinagar, probably a recent introduction. Closely related to Persicaria pubescens in overall features but differs by having erect racemes and smaller nuts whereas in P. pubescens the racemes are drooping and nuts are larger.

Polygonum punctatum Elliott, Sketch Bot. S. Carolina 1: 455. 1817; P. acre Kunth var. leptostachyum Meisner; P. punctatum var. confertiflorum (Meisner) Small; P. punctatum var. ellipticum Fassett; P. punctatum var. leptostachyum (Meisner) Small; P. punctatum var. parviflorum Fassett; P. punctatum var. parvum Marie-Victorin & Rousseau

Polygonum punctatum Elliott in Bot. Soc. Carol. Georgia 1: 55. 1817; R.R.Stewart, Ann. Cat. Vasc. Pl. W. Pak. & Kashm. 211. 1972.

Persicaria punctata (syn. Polygonum punctatum) is a species of flowering plant in the knotweed family known by the common names dotted smartweed and dotted knotweed.

Persicaria punctata is native to the Americas, where it can be found in moist and wet habitat types from Canada to Argentina including the West Indies. It is an extremely variable plant. It may be annual or perennial.

Persicaria punctata grows from a rhizome and produces decumbent or erect stems which may just exceed one meter (40 cm) in length. The branching stems may root at nodes that come in contact with the substrate. The lance-shaped leaves are up to 15 centimeters long and have stipules widened into bristly brown ochrea that wrap around the stems. The inflorescence is a number of branching clusters of dotted greenish flowers with white edges, sometimes tinged pink.