Persicaria lapathifolia |
Persicaria hydropiperoides |
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common knotweed, curltop knotweed, curltop ladysthumb, curlytop knotweed, dock-leaf smartweed, pale smartweed, renouée à feuilles de patience, willow weed |
false water pepper, false water-pepper smartweed, mild waterpepper, renouée faux-poivre-d'eau, swamp smartweed, water-pepper |
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Habit | Plants annual, (0.5–)1–10 dm; roots also sometimes arising from proximal nodes; rhizomes and stolons absent. | Plants perennial, 1.5–10 dm; roots also often arising from proximal nodes; rhizomes often 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, usually branched, without noticeable ribs, glabrous or obscurely strigose 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. |
ocrea brown, cylindric, 5–23 mm, chartaceous, base inflated, margins truncate, ciliate with bristles (2–)4–10 mm, surface glabrous or strigose, not glandular-punctate; petiole 0.2–2 cm, glabrous or strigose; blade without dark triangular or lunate blotch adaxially, broadly lanceolate to linear-lanceolate, 5–25 × 0.4–3.7 cm, base tapered or acute, margins antrorsely appressed-pubescent, apex acuminate, faces glabrous or appressed-pubescent along midveins and sometimes on faces, usually 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. |
terminal, sometimes also axillary, erect, uninterrupted or interrupted proximally, 30–80 × 2–5 mm; peduncle 10–30 mm, glabrous or strigose; ocreolae overlapping distally, often not overlapping proximally, margins ciliate with bristles to 2(–3) mm. |
Pedicels | ascending, 0.5–2.3 mm. |
ascending, 1–1.5 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. |
bisexual or unisexual and staminate, 2–6 per ocreate fascicle, homostylous; perianth roseate proximally, roseate, white, or greenish white distally, not glandular-punctate or sometimes glandular-punctate with punctae on tubes and inner tepals, scarcely accrescent; tepals 5, connate ca. 1/3–1/2 their length, obovate, 2.5–4 mm in bisexual flowers, 1.5–2.5 mm in staminate flowers, veins prominent or not, not anchor-shaped, margins entire, apex obtuse to rounded; stamens 8, included or exserted in staminate flowers; anthers pink or red, elliptic to ovate; styles 3, connate near middle. |
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, brown to brownish black or black, 3-gonous, 1.5–3 × 1–2.3 mm, shiny, smooth. |
2n | = 22. |
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Persicaria lapathifolia |
Persicaria hydropiperoides |
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Phenology | Flowering (Apr-)Jul–Nov. | Flowering Jun–Nov. |
Habitat | Moist places, roadsides, floodplains, waste places, cultivated fields | Wet banks and clearings, shallow water, marshes, moist prairies, ditches |
Elevation | 0-1500(-1800) m (0-4900(-5900) ft) | 0-1500 m (0-4900 ft) |
Distribution |
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)
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AK; AL; AR; AZ; CA; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; NC; ND; NE; NH; NJ; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; VA; VT; WA; WI; WV; BC; NB; NS; ON; QC; Mexico; Central America; South America
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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.) |
The extreme variability in Persicaria hydropiperoides is reflected in its extensive synonymy. Among the segregates most often recognized in floras and checklists is P. opelousana, which C. B. McDonald (1980) showed to be broadly sympatric and highly interfertile with P. hydropiperoides. Consistent with this conclusion, R. S. Mitchell (1971) found that P. hydropiperoides and P. opelousana are unique among native North American smartweeds in consistently possessing multicellular plate-glands on the abaxial surface of their leaves. Such glands also are found on P. maculosa, an introduced European species. Herbarium specimens of Persicaria hydropiperoides sometimes are misidentified as P. maculosa, especially when the roots are missing. The former species may be distinguished reliably by its achenes all trigonous (trigonous and biconvex achenes are mixed in the inflorescences of P. maculosa) and bristles on the margins of the ocreae that average longer. M. L. Fernald (1922c) reported hybrids with P. robustior from Nova Scotia. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 5, p. 589. | FNA vol. 5, p. 585. |
Parent taxa | Polygonaceae > subfam. Polygonoideae > Persicaria > sect. Persicaria | Polygonaceae > subfam. Polygonoideae > Persicaria > sect. Persicaria |
Sibling taxa | ||
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 hydropiperoides, P. opelousana, P. paludicola, Polygonum hydropiperoides var. adenocalyx, Polygonum hydropiperoides var. asperifolium, Polygonum hydropiperoides var. breviciliatum, Polygonum hydropiperoides var. bushianum, Polygonum hydropiperoides var. digitatum, Polygonum hydropiperoides var. opelousanum, Polygonum hydropiperoides var. psilostachyum, Polygonum opelousanum, Polygonum opelousanum var. adenocalyx |
Name authority | (Linnaeus) Gray: Nat. Arr. Brit. Pl. 2: 270. (1822) | (Michaux) Small: Fl. S.E. U.S., 378. (1903) |
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