Polygonum argyrocoleon |
Polygonum oxyspermum |
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Persian knotweed, silver sheath knotweed |
knotweed, sharp-fruit knotweed |
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Habit | Plants green, heterophyllous. | Plants green to blue-green, homophyllous. | ||||
Stems | erect or decumbent, branched mostly from base, not wiry, 15–100 cm. |
prostrate to ascending, branched at proximal and middle nodes, not wiry, 20–100 cm. |
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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 6.5–12 mm, proximal part cylindric, pruinose, distal part hyaline, soon disintegrating into brown fibers or nearly completely deciduous; petiole 0–1 mm; blade green to bluish green, elliptic-lanceolate to linear, 10–35 × 1.5–15 mm, margins flat or narrowly revolute, apex acute; middle stem leaves slightly larger than adjacent branch leaves, distal leaves overtopping flowers. |
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Inflorescence(s) | axillary and terminal, spikelike; cymes aggregated at tips of stems and branches, 4–6-flowered, bracts inconspicuous. |
axillary, cymes uniformly distributed, 2–7-flowered. |
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Pedicels | enclosed in ocreae, 1–2 mm. |
exserted from ocreae, 2.5–5(–7) mm. |
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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. |
semi-open; perianth 3.5–5.5 mm; tube 28–39% of perianth length; tepals slightly overlapping, green, margins white to pink, petaloid, not keeled, oblong to obovate, not cucullate; veins branched; stamens 8. |
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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. |
exserted from perianth, pale brown to dark brown, ovate, 3-gonous, (3.5–)4.1–5.5(–6.5) mm, faces subequal, apex not beaked, edges straight, shiny, smooth or with fine tubercles especially toward apex; late-season achenes unknown. |
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Polygonum argyrocoleon |
Polygonum oxyspermum |
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Phenology | Flowering May–Oct. | |||||
Habitat | Fields, gardens, disturbed sites, often in saline soils | |||||
Elevation | 0-1200 m (0-3900 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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ME; NB; NF; NS; PE; QC; Europe |
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Discussion | Subspecies 3 (2 in the flora). The treatment by D. A. Webb and A. O. Chater (1963) of the Polygonum oxyspermum complex is followed here. T. Karlsson (2000) accepted P. raii and P. oxyspermum as distinct species. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 5, p. 560. | FNA vol. 5, p. 554. | ||||
Parent taxa | Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Polygonum | Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Polygonum | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Name authority | Steudel ex Kunze: Linnaea 20: 17. (1847) | C. A. Meyer & Bunge ex Ledebour: Index Seminum (Dorpat) 1824: 5. (1824) | ||||
Web links |