Polygonum ramosissimum |
Polygonum austiniae |
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bushy knotweed, yellow knotweed, yellow-flower knotweed |
Austin's knotweed, Mrs. Austin's knotweed, Rebecca Austin's knotweed |
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Habit | Plants yellowish green or bluish green, (dark brown to black after drying in subsp. prolificum), heterophyllous or homophyllous. | Herbs. | ||||
Stems | erect, usually profusely branched in distal 1/2, not wiry, 10–100(–200) cm. |
ascending to erect, green to purplish, much-branched from base, not wiry, 5–10(–20) cm, papillose-scabridulous. |
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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. |
uniformly distributed, articulated to ocreae, basal leaves persistent, distal leaves abruptly reduced to bracts, articulated to ocreae; ocrea 3–5 mm, papillose-scabridulous or glabrous, proximal part funnelform, distal part lacerate; petiole 0.1–2 mm; blade 1-veined, not pleated, ovate to elliptic or obovate, 5–15 × 4–7 mm, margins flat or narrowly revolute, papillose-denticulate, apex acute or mucronate. |
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Inflorescences | axillary or axillary and terminal, spikelike; cymes uniformly distributed or crowded toward tips of branches, 2–5-flowered. |
axillary and terminal, spikelike, slender; cymes spaced along branches, 1–4-flowered. |
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Pedicels | enclosed in or exserted from ocreae, 1–6 mm. |
exserted from ocreae, reflexed, 1–2.5 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). |
closed; perianth (1.8–)2–2.6 mm; tube 20–28% of perianth length; tepals overlapping, green or purple, with narrow whitish margins, petaloid or sepaloid, oblong, cucullate, navicular, apex rounded; midveins unbranched; 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. |
enclosed in perianth, black, elliptic to obovate, 2–2.5 mm, faces subequal, shiny, ± smooth. |
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Polygonum ramosissimum |
Polygonum austiniae |
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Phenology | Flowering Jun–Sep. | |||||
Habitat | Dry to moist flats on banks, sagebrush plains, and ponderosa pine forests | |||||
Elevation | 1300-1600 m (4300-5200 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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CA; ID; MT; NV; OR; WA; WY; AB; BC
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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. 569. | ||||
Parent taxa | Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Polygonum | Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Duravia | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | P. douglasii subsp. austiniae | |||||
Name authority | Michaux: Fl. Bor.-Amer. 1: 237. (1803) | Greene: Bull. Calif. Acad. Sci. 1: 212. (1885) | ||||
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