Dock Leaf Smartweed

Nile Valley North of Nubia (Location: Delta), Nubian Desert Oases, Libyan Desert Oases.

Tropics of the Old World to Crete and Palestine.

Along canal banks and around springs.

Perennial.

Height: 0.6-1.5 m.

In Great Britain and/or Ireland:
Foodplant / pathogen
embedded sorus of Bauhinus reticulatus infects and damages live ovary of Persicaria lapathifolia

Foodplant / parasite
cleistothecium of Erysiphe polygoni parasitises live Persicaria lapathifolia

Foodplant / feeds on
larva of Phytobius quadricorniger feeds on Persicaria lapathifolia

Foodplant / spot causer
epiphyllous, immersed pycnidium of Septoria polygonorum causes spots on live leaf of Persicaria lapathifolia
Remarks: season: 7-10

Foodplant / pathogen
sorus of Sphacelotheca hydropiperis infects and damages live ovary of Persicaria lapathifolia
Remarks: season: 8-9

Persicaria lapathifolia is a morphologically variable complex with more than two-dozen infraspecific taxa described in the New World and Old World. An allozyme study by L. L. Consaul et al. (1991) did not support recognition of elements often referred to Polygonum lapathifolium var. salicifolium or P. scabrum, which are synonymized here. Yang J. and Wang J. W. (1991) reached a similar conclusion regarding var. salicifolium and P. nodosum based on their morphometric analysis.

The Keres, Navajo, and Potawatomi prepared medicinal infusions with Persicaria lapathifolia, and the Zuni used decoctions made from the plants as cathartic and emetic drugs (D. E. Moerman 1998).

Plants annual, (0.5-)1-10 dm; roots also sometimes arising from proximal nodes; rhizomes and stolons absent. Stems ascending to erect, simple or branched, scarcely ribbed, glabrous or, rarely, appressed-pubescent distally, sometimes glandular-punctate or stipitate-glandular distally. Leaves: ocrea brownish, cylindric, 4-24(-35) mm, chartaceous, base inflated, margins truncate, eciliate or ciliate with bristles to 1 mm, surface glabrous, rarely strigose, eglandular; petiole 0.1-1.6 cm, usually strigose, sometimes glabrous; blade sometimes with dark triangular or lunate blotch adaxially, narrowly to broadly lanceolate, 4-12(-22) × (0.3-)0.5-4(-6) cm, base tapering to cuneate, margins antrorsely scabrous, apex acuminate, faces strigose on main veins, glabrous or tomentose abaxially, glandular-punctate abaxially. Inflorescences mostly terminal, sometimes also axillary, mostly arching or nodding, usually uninterrupted, 30-80 × 5-12 mm; peduncle 2-25 mm, often stipitate-glandular; ocreolae usually overlapping, margins eciliate or ciliate with bristles to 0.4 mm. Pedicels ascending, 0.5-2.3 mm. Flowers 4-14 per ocreate fascicle, homostylous; perianth greenish white to pink, glabrous, not glandular-punctate or glandular-punctate with punctae mostly on tubes and inner tepals, scarcely accrescent; tepals 4(-5), connate ca. 4- 3 their length, obovate to elliptic, 2.5-3 mm, veins prominent, those of 2 or 3 outer tepals prominently bifurcate distally, anchor-shaped, margins entire, apex obtuse to rounded; stamens 5-6, included; anthers pink or red, elliptic; styles 2(-3), connate at bases. Achenes included or apex exserted, brown to black, discoid or, rarely, 3-gonous, 1.5-3.2 × 1.6-3 mm, shiny or dull, smooth. 2n = 22.

Annual, erect or ascending, 20-60 cm tall, annual herb, glabrous or pubescent. Stem simple or branched, often thickened at the nodes, usually with red dots, internodes usually shorter than the leaves. Leaves distinctly petiolate, linear lanceolate, acute to acuminate, (1.5-) 2-10 (-12) x 0.5-2.0 (-2.5) cm, entire, ciliate on margins, midrib and veins, ± tomentose below or glabrous (var. nodosa) sometimes covered with yellow glands. Ochrea 5-20 (-30) mm long, tubular, ovate, ± brownish entire-dentate, eciliate, rarely very finely ciliate at the mouth. Inflorescence many flowered dense, pedunculate, uninterrupted or lax, 1-5 cm long, curved or stiff raceme; peduncle as long as the inflorescence or less, glandular or not. Flowers up to 2.5 mm across, subsessile to pedicellate, pedicel 0.5-1 (-1.5) mm long. Ochreolae 0.5-3 mm long, ovate, acuminate, eciliate, entire to dentate. Tepals 4-5, in two whorls, pink or white or greenish with a reddish tinge, unequal, elliptic-obovate, obtuse, entire. c. 2.0 x 0.75 mm, glandular, glands sessile, yellow. Stamens 5-6 (-8), filaments long, unequal, ovary biconvex, c. 1 mm long, with two styles, styles filiform, free above, fused below, stigmas capitate. Nuts 2-3.5 x 1.5-2.0 mm, biconvex, slightly compressed in the middle, circular to broadly ovate, shining, black-brown.

A fairly common and widespread species, grows from plains to 3000 m in moist and shady areas. A highly polymorphic taxon especially in habit, presence or absence of red dots on the stem, colour of the glands on the leaves and perianth, tomentose to almost glabrous leaves, eglandular to glandular peduncle and length and compactness of raceme. The variation in our area in most of the characters is continuous. However, the character of leaf indumentum and length and compactness of raceme seem to be fairly stable. Therefore two varieties are recognized in our region.

Plants perennial, rhizomatous. Stems erect, sometimes prostrate below, 80-100 cm tall, robust, simple, pilose or glabrescent. Petiole 1-2 cm; leaf blade broadly lanceolate, 10-15 × 1.5-3 cm, both surfaces densely sericeous, base narrowly cuneate, margin entire, ciliate, apex long acuminate; ocrea tubular, 1.5-2 cm, membranous, densely pubescent, apex truncate, cilia 4-6 mm. Inflorescence terminal, of panicled spikes, erect, 3-6 cm; bracts ovate, adpressed hispidulous, each 3- or 4-flowered. Pedicels longer than bracts. Perianth white, 5-parted; tepals elliptic, 3-3.5 mm. Stamens 7 or 8, included. Styles 2, free; stigmas capitate. Achenes included in persistent perianth, black, shiny, orbicular, biconvex, 3-4 mm in diam. Fl. Sep-Oct, fr. Oct-Nov.

Greenland; St. Pierre and Miquelon; Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Ont., P.E.I., Que., Sask., Yukon; Ala., Alaska, 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., Nev., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis., Wyo.; Mexico; South America; Europe; Asia; Africa; Pacific Islands (New Zealand).

Guangdong, Guangxi, Taiwan [India, Indonesia, Malaysia, Myanmar, Philippines, Sri Lanka, Thailand; ?Africa, Australia].

Flowering (Apr-)Jul-Nov.

Moist places, roadsides, floodplains, waste places, cultivated fields; 0-1500(-1800)m.

In shallow water of swamps, marshy areas; 100-300 m.

Persicaria attenuata subsp. pulchra (Blume) K. L. Wilson; P. pulchra (Blume) Soják; Polygonum tomentosum Willdenow (1799), not Schrank (1789).

Polygonum lapathifolium Linnaeus, Sp. Pl. 1: 360. 1753; P. incarnatum Elliott; P. lapathifolium var. ovatum A. Braun; P. lapathifolium var. salicifolium Sibthorp; P. linicola Sutulov; P. nodosum Persoon; P. pensylvanicum Linnaeus var. oneillii (Brenckle) Hultén; P. scabrum Moench; P. tomentosum Willdenow

Robust erect semi aquatic annual herb, up to 3 m.

Frequent

Native of Europe.

Wikispecies has information related to Persicaria lapathifolia.

Persicaria lapathifolia (syn. Polygonum lapathifolium), known as pale persicaria, is a plant of the family Polygonaceae. It is closely related to Persicaria maculosa and as such is considered a weed in Britain and Europe. Other common names for the plant include pale smartweed, curlytop knotweed, and willow weed. It is a species complex made up of a great many varying forms, sometimes considered varieties. The environment also has a strong influence on the morphology of an individual plant.