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common knotweed, curltop knotweed, curltop ladysthumb, curlytop knotweed, dock-leaf smartweed, pale smartweed, renouée à feuilles de patience, willow weed

hairy smartweed

Habit Plants annual, (0.5–)1–10 dm; roots also sometimes arising from proximal nodes; rhizomes and stolons absent. Plants perennial, 3–9 dm; roots also often arising from proximal nodes; rhizomes present.
Stems

ascending to erect, simple or branched, scarcely ribbed, glabrous or, rarely, appressed-pubescent distally, sometimes glandular-punctate or stipitate-glandular distally.

decumbent to ascending or erect, branched, without noticeable ribs, brownish-hirsute on internodes.

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.

ocrea brown to reddish brown, cylindric, 6–12 mm, chartaceous, base sometimes inflated, margins truncate, eciliate or ciliate with bristles 4–7.5 mm, surface hirsute, not glandular-punctate;

petiole 0.1(–0.3) cm, hirsute, leaves sometimes sessile;

blade without dark triangular or lunate blotch adaxially, ovate to lanceolate, (2–)4–8 × (0.5–)1–2.5 cm, base rounded to cordate, margins strigose to hirsute, apex acute to acuminate, faces sparingly hirsute abaxially and adaxially, midvein usually hirsute 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.

mostly terminal, erect, interrupted proximally, usually uninterrupted distally, 20–80 × 4–8 mm;

peduncle 30–60 mm, hirsute or, sometimes, nearly glabrous distally;

ocreolae overlapping distally, usually not overlapping proximally, margins ciliate with bristles 0.4–1.5(–2) mm.

Pedicels

ascending, 0.5–2.3 mm.

ascending, 1–2 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. 1/4–1/3 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.

1–3 per ocreate fascicle, homostylous;

perianth white to pink, glabrous, not glandular-punctate, nonaccrescent;

tepals 5, connate in proximally 1/3, obovate, 1.5–2 mm, veins not prominent, not anchor-shaped, margins entire, apex obtuse to rounded;

stamens 5, included;

anthers red, elliptic to ovate;

styles 3, connate proximally.

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.

included or apex exserted, dark brown to brownish black, 3-gonous, 2–2.5 × 1.3–1.8 mm, shiny, smooth.

2n

= 22.

= 20.

Persicaria lapathifolia

Persicaria hirsuta

Phenology Flowering (Apr-)Jul–Nov. Flowering Jun–Oct.
Habitat Moist places, roadsides, floodplains, waste places, cultivated fields Sandy soils, open areas in savannahs, pond margins, ditches, often in shallow water
Elevation 0-1500(-1800) m (0-4900(-5900) ft) 0-100 m (0-300 ft)
Distribution
from FNA
AK; 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; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NL; NS; NT; ON; PE; QC; SK; YT; SPM; Mexico; South America; Africa; Greenland; Asia; Europe; Pacific Islands (New Zealand)
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; FL; GA; MS; NC; SC
[BONAP county map]
Discussion

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).

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

C. B. McDonald (1980) showed that Persicaria hirsuta is closely related to P. setacea and P. hydropiperoides. Hybrids between P. hirsuta and P. setacea have been produced experimentally but appear to be rare in the wild. Although geographically sympatric, the two species generally occupy different habitats. Experimental crosses between P. hirsuta and P. hydropiperoides were unsuccessful (McDonald).

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

Source FNA vol. 5, p. 589. FNA vol. 5, p. 587.
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. 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
P. amphibia, P. arifolia, P. bicornis, P. bungeana, P. capitata, P. careyi, P. chinensis, P. glabra, 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 lapathifolium, Polygonum incarnatum, Polygonum lapathifolium var. ovatum, Polygonum lapathifolium var. salicifolium, Polygonum linicola, Polygonum nodosum, Polygonum pensylvanicum var. oneillii, Polygonum scabrum, Polygonum tomentosum Polygonum hirsutum
Name authority (Linnaeus) Gray: Nat. Arr. Brit. Pl. 2: 270. (1822) (Walter) Small: Fl. S.E. U.S., 379. (1903)
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