Polygonum argyrocoleon |
Polygonum erectum |
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Persian knotweed, silver sheath knotweed |
devil's shoestring, erect knotweed, renouée dressée, upright knotweed, wireweed |
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Habit | Plants green, heterophyllous. | Plants light green or yellowish, heterophyllous. |
Stems | erect or decumbent, branched mostly from base, not wiry, 15–100 cm. |
erect to ascending, sparingly branched in distal 1/2, not wiry, 15–75 cm. |
Leaves | ocrea 4–8 mm, proximal part cylindric, distal part soon disintegrating into curly or straight fibers; petiole 0–1.5 mm; blade bluish green, lanceolate or linear-lanceolate, 15–50 × 2–8 mm, margins flat, apex acute; stem leaves 2.1–4 times as long as branch leaves; distal leaves abruptly reduced and not overtopping flowers (shorter than or equaling flowers). |
ocrea 7–12 mm, proximal part cylindric, distal part usually persistent, with strong veins, margins entire or lacerate, silvery, later disintegrating into ± persistent brown fibers; petiole 1–5 mm; blade light green or yellowish, elliptic to obovate, 30–60(–80) × (8–)10–25 mm, margins flat, apex obtuse; stem leaves 1.5–3.5(–4) times longer than branch leaves; distal leaves overtopping flowers in distal part of inflorescence. |
Inflorescence(s) | axillary and terminal, spikelike; cymes aggregated at tips of stems and branches, 4–6-flowered, bracts inconspicuous. |
axillary; cymes in axils of most leaves and toward tips of stems and branchs, 1–5-flowered. |
Pedicels | enclosed in ocreae, 1–2 mm. |
mostly exserted from ocreae, 3–7 mm. |
Flowers | closed; perianth 1.8–2.4 mm; tube 10–22% of perianth length; tepals overlapping, green or white, usually with pink, rarely red or white, margins, petaloid, not keeled, oblong to obovate, cucullate; midveins usually unbranched; stamens 7–8. |
closed; perianth 2.8–3.8(–4.2) mm; tube 20–37% of perianth length; tepals overlapping, green with yellowish, rarely whitish green, margins, sepaloid, not keeled, oblong to obovate, cucullate; midveins branched, moderately to heavily thickened; stamens 7–8. |
Achenes | enclosed in perianth, brown, ovate, 3-gonous, 1.3–2.3 mm, faces subequal, slightly concave, apex not beaked, with concave edges, shiny, smooth; late-season achenes unknown. |
enclosed in perianth, brown to tan, ovate, 3-gonous, 2.3–3.5 mm, faces subequal, ± concave, apex not beaked, edges concave, dull, striate-tubercled; late-season achenes uncommon, 4–5 mm. |
Polygonum argyrocoleon |
Polygonum erectum |
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Phenology | Flowering May–Oct. | Flowering May–Oct. |
Habitat | Fields, gardens, disturbed sites, often in saline soils | Dry, waste ground |
Elevation | 0-1200 m (0-3900 ft) | 10-300 m (0-1000 ft) |
Distribution |
AZ; CA; CO; FL; ID; LA; MA; MO; NC; NM; NV; TX; UT; VT; WV; c Asia [Introduced in North America]
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AL; AR; CO; CT; DC; DE; GA; IA; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; TN; VA; VT; WA; WI; WV; WY; AB; ON; QC; SK
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Discussion | Polygonum erectum was cultivated in the midwest by Native Americans for its starchy seeds (C. M. Scarry 1993). It was formerly confused with P. achoreum (T. R. Mertens and P. H. Raven 1965). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 5, p. 560. | FNA vol. 5, p. 550. |
Parent taxa | Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Polygonum | Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Polygonum |
Sibling taxa | ||
Name authority | Steudel ex Kunze: Linnaea 20: 17. (1847) | Linnaeus: Sp. Pl. 1: 363. (1753) |
Web links |
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