Polygonum ramosissimum |
Polygonum ramosissimum subsp. prolificum |
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bushy knotweed, yellow knotweed, yellow-flower knotweed |
bushy knotweed, proliferous knotweed, renouée prolifique |
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Habit | Plants yellowish green or bluish green, (dark brown to black after drying in subsp. prolificum), heterophyllous or homophyllous. | Plants bluish green when fresh, dark brown or black after drying, homophyllous. | ||||
Stems | erect, usually profusely branched in distal 1/2, not wiry, 10–100(–200) cm. |
10–80 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. |
blades bluish green, oblanceolate, 8–30(–35) × 4–6 mm, apex rounded or obtuse; stem leaves 1–2.5(–3.5) times as long as 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 or crowded toward tips of branches, 2–4-flowered. |
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Pedicels | enclosed in or exserted from ocreae, 1–6 mm. |
enclosed in ocreae, 1–2 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). |
perianth 2–2.8(–3) mm; tepal margins white or pink; stamens 3. |
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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. |
enclosed in or exserted from perianth, 1.6–2(–2.4) mm, shiny or dull, smooth, roughened, or obscurely tubercled; late-season achenes 4–10 mm. |
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2n | = 60. |
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Polygonum ramosissimum |
Polygonum ramosissimum subsp. prolificum |
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Phenology | Flowering Jul–Nov. | |||||
Habitat | Wet, saline places | |||||
Elevation | 0-2000 m (0-6600 ft) | |||||
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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AR; CA; CT; DE; IA; ID; IL; KS; KY; LA; MA; MD; ME; MN; MS; NC; ND; NH; NJ; NM; NY; OK; OR; PA; RI; SD; TN; TX; UT; VA; VT; WA; WV; WY; AB; BC; MB; ON; PE; QC; SK |
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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.) |
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Key |
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Source | FNA vol. 5, p. 551. | FNA vol. 5, p. 552. | ||||
Parent taxa | Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Polygonum | Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Polygonum > Polygonum ramosissimum | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | P. ramosissimum var. prolificum, P. prolificum, P. prolificum var. autumnale, P. prolificum var. profusum | |||||
Name authority | Michaux: Fl. Bor.-Amer. 1: 237. (1803) | (Small) Costea & Tardif: Sida 20: 995. (2003) | ||||
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