Persicaria sagittata |
Persicaria longiseta |
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arrow-leaf knotweed, arrow-leaf tearthumb, arrow-vine, renouée sagittée |
bristly lady's-thumb, oriental lady's thumb, oriental lady's-thumb smartweed |
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Habit | Plants annual, 3–20 dm; roots also often arising from proximal nodes. | Plants annual, 3–8 dm; roots also often arising from proximal nodes; rhizomes and stolons absent. |
Stems | scandent, ribbed, glabrous; prickles 1–1.5 mm. |
decumbent to ascending, branched, without noticeable ribs, glabrous. |
Leaves | ocrea brownish, cylindric, (3–)5–13 mm, chartaceous, base inflated or not, without prickles, margins oblique, glabrous or ciliate at tip with bristles 0.2–1 mm, surface glabrous; petiole 0.5–4 cm; blade broadly lanceolate to oblong, 2–8.5 × 1–3 cm, base sagittate to cordate, margins entire, ciliate or eciliate, apex obtuse to acute, faces glabrous or densely appressed-pubescent, usually with retrorse prickles along midvein abaxially. |
ocrea hyaline to brownish, cylindric, 5–12 mm, chartaceous, base sometimes inflated, margins truncate, ciliate with bristles 4–12 mm, surface glabrous or strigose, not glandular-punctate; petiole 0.1–0.3(–0.6) cm, glabrous, leaves sometimes sessile; blade without dark triangular or lunate blotch adaxially, ovate-lanceolate to linear-lanceolate, 2–8 × 1–3 cm, base tapering to cuneate, margins antrorsely strigose, apex acute to acuminate, faces glabrous or sparingly strigose along veins abaxially, glabrous or strigose along midvein and margins adaxially, not glandular-punctate. |
Inflorescences | capitate or paniclelike, uninterrupted, 5–15 × 4–10 mm; peduncle 10–80 mm, usually glabrous, sometimes with retrorse prickles proximally; ocreolae overlapping, margins eciliate. |
terminal, sometimes also axillary, erect, uninterrupted, 10–40(–80) × 3–7 mm; peduncle 10–50 mm, glabrous; ocreolae overlapping, margins ciliate with bristles (0.5–)1–4(–6) mm. |
Pedicels | mostly ascending, 1–1.5 mm. |
ascending, 1–2 mm. |
Flowers | 2–3 per ocreate fascicle; perianth white or greenish white, often tinged pink or red, sometimes entirely pink, glabrous, accrescent, not becoming blue and fleshy in fruit; tepals 5, connate 1/3–1/2 their length, broadly elliptic, 3–5 mm, apex obtuse; stamens 8, filaments distinct, free; anthers pink, ovate; styles 3, connate to middle. |
1–5 per ocreate fascicle, homostylous; perianth pinkish green proximally, roseate distally, glabrous, not glandular-punctate, scarcely accrescent; tepals 5, connate ca. 1/3 their length, obovate, 2.2–2.8 mm, veins not prominent, not anchor-shaped, margins entire, apex obtuse to rounded; stamens 5, included; anthers yellow, elliptic to ovate; styles 3, connate proximally. |
Achenes | included or styles exserted, light or dark brown to black, 3-gonous, 2.5–4 × 1.8–2.5 mm, dull to shiny, smooth to minutely punctate. |
included, dark brown to black, 3-gonous, 1.6–2.3 × 1.1–1.6 mm, shiny, smooth. |
2n | = 40. |
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Persicaria sagittata |
Persicaria longiseta |
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Phenology | Flowering Jun–Oct. | Flowering May–Oct. |
Habitat | Moist shaded sites, meadows, pastures, fens, swamps, shorelines of ponds and streams | Floodplain forests and woodlands, shorelines of ponds, moist roadsides, waste places |
Elevation | 0-1000 m (0-3300 ft) | 0-300 m (0-1000 ft) |
Distribution |
AL; AR; CO; CT; DC; DE; FL; GA; IA; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; NC; ND; NE; NH; NJ; NY; OH; OK; PA; RI; SC; SD; TN; TX; VA; VT; WI; WV; MB; NB; NF; NS; ON; PE; QC; e Asia
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AL; CT; DE; FL; GA; IA; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; NC; NE; NJ; NY; OH; PA; SC; TN; TX; VA; VT; WI; WV; BC; NB; ON; e Asia [Introduced in North America; introduced also in Europe]
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Discussion | Persicaria sagittata is an extremely variable species. Achene and leaf characters have been used by some authors to separate North American and Asian populations, but these characters show weak geographic variation (C. W. Park 1988). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Persicaria longiseta is morphologically similar to another Asian species, P. posumbu (Buchanan-Hamilton ex D. Don) H. Gross (= P. caespitosa). Its spread in the United States since its introduction near Philadelphia in 1910 was summarized by A. K. Paterson (2000). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 5, p. 577. | FNA vol. 5, p. 592. |
Parent taxa | Polygonaceae > subfam. Polygonoideae > Persicaria > sect. Echinocaulon | Polygonaceae > subfam. Polygonoideae > Persicaria > sect. Persicaria |
Sibling taxa | ||
Synonyms | Polygonum sagittatum, Polygonum sagittatum var. gracilentum, Tracaulon sagittatum, Truellum sagittatum | Polygonum longisetum, P. caespitosa var. longiseta, Polygonum caespitosum var. longisetum |
Name authority | (Linnaeus) H. Gross: Beih. Bot. Centralbl. 37(2): 113. (1919) | (Bruijn) Kitagawa: Rep. Inst. Sci. Res. Manchoukuo 1: 322. (1937) |
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