Persicaria hydropiper |
Persicaria glabra |
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common smartweed, marsh-pepper smartweed, marshpepper knotweed, mild water-pepper, renouée poivre-d'eau, smartweed, water-pepper, water-pepper smartweed |
denseflower knotweed, smooth smartweed |
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Habit | Plants annual, 2–8(–10) dm; roots also often arising from proximal nodes; rhizomes and stolons absent. | Plants perennial, 3–15 dm; roots also often arising from proximal nodes; rhizomes present. |
Stems | decumbent to ascending or erect, branched, without noticeable ribs, glabrous, glandular-punctate. |
decumbent to erect, usually branched distally, without noticeable ribs, glabrous or, rarely, pubescent distally, sometimes glandular-punctate. |
Leaves | ocrea brown, cylindric or funnelform, (8–)10–15 mm, chartaceous, base inflated, margins truncate, ciliate with bristles 1–4 mm, surface glabrous or strigose, usually glandular-punctate; petiole 0.1–0.8 cm, glandular-punctate, leaves sometimes sessile; blade without dark triangular or lunate blotch adaxially, lanceolate to narrowly rhombic, (1.5–)4–10(–15) × 0.4–2.5 cm, base tapered or cuneate, margins antrorsely strigose, apex acute to acuminate, faces glabrous or scabrous along midveins, glandular-punctate, sometimes obscurely so adaxially. |
ocrea light brown, cylindric, 12–23 mm, chartaceous, base inflated, margins truncate, eciliate, surface glabrous, usually obscurely glandular-punctate; petiole 0.2–2 cm, scabrous; blade without dark triangular or lunate blotch adaxially, lanceolate, (10–)15–30 × (1.5–)2–5.4 cm, base tapered, margins glabrous or antrorsely strigose, apex acute to acuminate, faces glabrous or scabrous along midveins, sometimes glandular-punctate. |
Inflorescences | terminal and axillary, erect or nodding, interrupted or uninterrupted distally, 30–180 × 5–9 mm; peduncle (0–)10–50 mm, sometimes absent on axillary inflorescences and flowers thus enclosed in ocreae, glabrous, glandular-punctate; ocreolae not overlapping or overlapping distally, margins eciliate or ciliate with bristles to 1 mm. |
mostly terminal, sometimes also axillary, erect to slightly nodding, usually uninterrupted, 30–100 × 5–9 mm; peduncle 10–50 mm, glabrous or scabrid, glandular-punctate; ocreolae usually overlapping, margins eciliate. |
Pedicels | ascending, 1–3 mm. |
erect to spreading, 2–5 mm. |
Flowers | 1–3(–5) per ocreate fascicle, homostylous; perianth greenish proximally, white or pink distally, glandular-punctate with punctae ± uniformly distributed, scarcely accrescent; tepals 4–5, connate ca. 1/3 their length, petaloid, obovate, 2–3.5 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. |
(1–)3–8 per ocreate fascicle, homostylous; perianth greenish white to white or pink, glabrous, not glandular-puncate or glandular-punctate with punctae ± uniformly distributed, scarcely accrescent; tepals 5, connate ca. 1/3 their length, obovate, 3–3.6 mm, veins not prominent, not anchor shaped, margins entire, apex obtuse to rounded; stamens 5–7, included; anthers pink or red, ovate; styles 2, connate proximally. |
Achenes | included or apex exserted, brownish black, biconvex or 3-gonous, 1.9–3 × 1.5–2 mm, dull, minutely roughened. |
included, dark brown to brownish black, biconvex, 2–2.2 × 1.3–1.6 mm, shiny, smooth. |
2n | = 20. |
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Persicaria hydropiper |
Persicaria glabra |
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Phenology | Flowering May–Nov. | Flowering Aug–Nov. |
Habitat | Shorelines of lake and ponds, banks of streams and rivers, fens, forested wetlands, pastures, occasionally waste ground | Swamps, wet thickets, marshy shores, frequently in water, mostly on coastal plain of e North America |
Elevation | 0-1500 m (0-4900 ft) | 0-300 |
Distribution |
AK; AL; AR; 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; BC; MB; NB; NF; NS; ON; PE; QC; SPM; Europe; nw Africa; Pacific Islands (Hawaii, New Zealand); Australia [Introduced in North America; introduced also in Asia]
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AL; AR; DE; FL; GA; KY; LA; MD; MO; MS; NC; NJ; SC; TN; TX; VA; Central America; South America; Asia; ne Africa; Pacific Islands (Hawaii, Philippines)
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Discussion | All parts of Persicaria hydropiper have an acrid, pepperlike taste. The plants have a long history of medicinal use in Europe, and the oily exudate produced in multicellular glands can cause skin irritation, hence the common name smartweed (R. S. Mitchell and J. K. Dean 1978). Some Native American tribes used P. hydropiper as a drug to treat a variety of ailments, and the Cherokee and Iroquois consumed it as food (D. E. Moerman 1998). Herbarium specimens of Persicaria hydropiper often are misidentified as P. punctata. In addition to its minutely roughened and dull achenes, P. hydropiper differs from P. punctata frequently in bearing flowers enclosed in the ocreae, the inflorescences thus appearing somewhat leafy. By contrast, inflorescences of P. punctata generally appear terminal and leafless. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
American plants here included in Persicaria glabra often have been treated as distinct and called P. densiflora. The morphological differences between them and Asian and Pacific P. glabra are minor. Regional tendencies exist but do not appear sufficient to warrant separation of the species (K. L. Wilson 1990b). An infusion made from pounded whole plants was used by the Hawaiians as a blood medicine (D. E. Moerman 1998). Persicaria portoricensis Small and Polygonum portoricense Bertero ex Small are superfluous and illegitimate names that pertain here. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 5, p. 590. | FNA vol. 5, p. 586. |
Parent taxa | Polygonaceae > subfam. Polygonoideae > Persicaria > sect. Persicaria | Polygonaceae > subfam. Polygonoideae > Persicaria > sect. Persicaria |
Sibling taxa | ||
Synonyms | Polygonum hydropiper, Polygonum hydropiper var. projectum | Polygonum glabrum, P. densiflora, Polygonum densiflorum |
Name authority | (Linnaeus) Spach: Hist. Nat. Vég. 10: 536. (1841) | (Willdenow) M. Gómez: Anales Inst. Segunda Enseñ. 2: 278. (1896) |
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