Polygonum ramosissimum |
Polygonum oxyspermum |
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bushy knotweed, yellow knotweed, yellow-flower knotweed |
knotweed, sharp-fruit knotweed |
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Habit | Plants yellowish green or bluish green, (dark brown to black after drying in subsp. prolificum), heterophyllous or homophyllous. | Plants green to blue-green, homophyllous. | ||||||||
Stems | erect, usually profusely branched in distal 1/2, not wiry, 10–100(–200) cm. |
prostrate to ascending, branched at proximal and middle nodes, not wiry, 20–100 cm. |
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Leaves | ocrea 6–12(–15) mm, proximal part cylindric, distal part silvery, soon disintegrating into persistent brown fibers; petiole 2–4 mm; blade variable, light yellowish green to bluish green, proximal often caducous, narrowly elliptic, lanceolate, or oblanceolate, rarely ovate, 8–70 × 4–18(–35) mm, margins flat, apex acute to acuminate or obtuse; distal leaves, either overtopping or 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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Inflorescences | axillary or axillary and terminal, spikelike; cymes uniformly distributed or crowded toward tips of branches, 2–5-flowered. |
axillary, cymes uniformly distributed, 2–7-flowered. |
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Pedicels | enclosed in or exserted from ocreae, 1–6 mm. |
exserted from ocreae, 2.5–5(–7) mm. |
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Flowers | closed; perianth (2–)2.2–3.6(–4) mm; tube 20–38% of perianth length; tepals overlapping, greenish yellow with greenish yellow or yellow, rarely pink or white, margins, petaloid or sepaloid, not keeled, elliptic to oblong, cucullate; midveins thickened or not; stamens 3–6(–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 or exserted from perianth, dark brown, ovate, 3-gonous, 1.6–3.5 mm, faces subequal, concave, apex not beaked, edges straight, shiny or dull, usually smooth to roughened, sometimes uniformly or obscurely tubercled; late-season achenes common, 4–15 mm. |
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 ramosissimum |
Polygonum oxyspermum |
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Distribution |
AR; AZ; CA; CO; CT; DE; 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; NS; NT; ON; PE; QC; SK
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ME; NB; NF; NS; PE; QC; Europe |
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Discussion | Subspecies 2 (2 in the flora). Polygonum ramosissimum exhibits considerable morphological complexity and is similar in difficulty to the P. aviculare complex. Further research is necessary to understand the infraspecific variability of this species (M. Costea and F. J. Tardif 2003b). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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. 551. | FNA vol. 5, p. 554. | ||||||||
Parent taxa | Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Polygonum | Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Polygonum | ||||||||
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Subordinate taxa | ||||||||||
Name authority | Michaux: Fl. Bor.-Amer. 1: 237. (1803) | C. A. Meyer & Bunge ex Ledebour: Index Seminum (Dorpat) 1824: 5. (1824) | ||||||||
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