Polygonum bidwelliae |
Polygonum ramosissimum |
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Bidwell knotweed, Bidwell's knotweed |
bushy knotweed, yellow knotweed, yellow-flower knotweed |
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Habit | Herbs. | Plants yellowish green or bluish green, (dark brown to black after drying in subsp. prolificum), heterophyllous or homophyllous. | ||||
Stems | erect, green, simple or divaricately branched, ± wiry, 2–20 cm, minutely papillose-scabridulous. |
erect, usually profusely branched in distal 1/2, not wiry, 10–100(–200) cm. |
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Leaves | crowded at branch tips, not articulated to ocreae, basal leaves caducous or persistent, distal leaves abruptly reduced to bracts; ocrea 8–13 mm, papillose-scabridulous, proximal part cylindric, distal part overlapping and obscuring leaves and flowers, silvery, entire or shallowly dentate; petiole absent; blade 3-veined, without pleats, linear, 5–15(–20) × 0.5–1.5(–2) mm, margins revolute, papillose-denticulate, apex spine-tipped. |
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. |
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Inflorescences | axillary; cymes in distal axils, 1-flowered. |
axillary or axillary and terminal, spikelike; cymes uniformly distributed or crowded toward tips of branches, 2–5-flowered. |
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Pedicels | absent. |
enclosed in or exserted from ocreae, 1–6 mm. |
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Flowers | closed; perianth 2–3 mm; tube 10–18% of perianth length; tepals overlapping, pink with pink or white margins, petaloid, elliptic, navicular, apex acute to acuminate; midveins unbranched; stamens 8. |
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). |
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Achenes | enclosed in perianth at maturity, light brown to brown, ovate-elliptic, 1.8–2.3 mm, faces subequal, shiny, smooth. |
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. |
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Polygonum bidwelliae |
Polygonum ramosissimum |
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Phenology | Flowering May–Jun. | |||||
Habitat | Thin volcanic soils, chaparral, montane woodland valleys, grasslands | |||||
Elevation | 60-1200 m (200-3900 ft) | |||||
Distribution |
CA
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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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Discussion | Polygonum bidwelliae occurs in the Cascade Range and northeastern Sacramento Valley in Butte, Shasta, and Tehama counties. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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. 565. | FNA vol. 5, p. 551. | ||||
Parent taxa | Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Duravia | Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Polygonum | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Name authority | S. Watson: Proc. Amer. Acad. Arts 14: 294. (1879) | Michaux: Fl. Bor.-Amer. 1: 237. (1803) | ||||
Web links |
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