Polygonum polygaloides |
Polygonum nuttallii |
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close-flower knotweed, close-flower knotweed (ssp. confertiflorum), Kellogg's knotweed (ssp. kelloggii), milkwort knotweed, polygala knotweed, whitemargin knotweed |
Nuttall's knotweed |
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Habit | Herbs. | Herbs. | ||||||||||||||||
Stems | erect, green, usually divaricately branched, rarely simple, ± wiry, (2–)6–20(–25) cm, glabrous. |
spreading to erect, sometimes zigzagged, purplish, simple or branched, wiry, (5–)10–35 cm, papillose-scabridulous. |
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Leaves | uniformly distributed, articulated to ocreae, basal leaves often caducous, distal leaves abruptly reduced to bracts; ocrea 4–8 mm, glabrous, proximal part cylindric, distal part silvery, with inconspicuous veins, lacerate; petiole absent; blade 3-veined, lateral veins sometimes inconspicuous, without pleats, narrowly linear, 10–40 × 1–2.5 mm, margins ± revolute, smooth, apex acute or mucronate. |
evenly distributed or crowded at branch tips, articulated to ocreae, basal leaves persistent, distal leaves gradually reduced to bracts; ocrea 3–4 mm, papillose-scabridulous, proximal part funnelform, distal part finely lacerate; petiole 0.1–2 mm; blade 1-veined, not pleated, linear to narrowly oblong-elliptic, 8–30 × 1–4(–7) mm, margins narrowly revolute, never touching along midrib, smooth, apex acute, mucronate, ± glaucous adaxially. |
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Inflorescences | axillary and terminal, spikelike, subglobose to cylindric; cymes in most axils or crowded distally, 1–3-flowered. |
axillary and terminal, spikelike, dense; cymes mostly congested toward tips of branches, 2–3-flowered. |
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Pedicels | enclosed in ocreae, erect, 0.1–2 mm, sometimes absent. |
enclosed in ocreae, erect to spreading, 2–3 mm. |
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Flowers | mostly closed; perianth 1.5–3 mm; tube 19–40% of perianth length; tepals overlapping, uniformly white, pink, or red, petaloid, oblong-lanceolate, ± navicular, apex acute to acuminate; midveins usually unbranched or with 2 lateral branches proximally, moderately to strongly thickened, tepals appearing ± keeled; stamens 3–8. |
semi-open or closed; perianth 1.8–2.4 mm; tube 25–33% of perianth length; tepals overlapping, greenish, white, or pink with pink margins, petaloid, oblong, cucullate, navicular in distal 1/4, apex rounded; midveins unbranched; stamens 8. |
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Achenes | enclosed in perianth, light yellow, light brown, or greenish brown to dark brown, ovate to lanceolate, 1.3–2.5 mm, faces subequal, shiny or dull, smooth or reticulate with longitudinal ridges. |
enclosed in perianth, black, elliptic to ovate, 1.8–2.3 mm, faces subequal, shiny, smooth. |
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Polygonum polygaloides |
Polygonum nuttallii |
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Phenology | Flowering May–Oct. | |||||||||||||||||
Habitat | Dry prairies, open knolls in lower mountains, open sites in lowland and montane zones, sandy soil | |||||||||||||||||
Elevation | 800-1100 m (2600-3600 ft) | |||||||||||||||||
Distribution |
AZ; CA; CO; ID; MT; NM; NV; OR; UT; WA; WY; AB; BC; SK
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OR; WA; BC
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Discussion | Subspecies 4 (4 in the flora). J. C. Hickman’s (1993c) treatment of the Polygonum polygaloides complex is provisionally accepted here. Most of the intermediate specimens occur between subspp. confertiflorum, esotericum, and kelloggii. Alternatively, P. polygaloides could be recognized in the narrow sense and the three other taxa could be treated as subspecies of a separate P. kelloggii, the earliest available binomial. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
C. L. Hitchcock (1964) suggested that Polygonum nuttallii is but a small-flowered form of P. spergulariiforme. Although morphologically similar, P. nuttallii differs from P. spergulariiforme in some respects, including its wiry, purplish stems, short and funnelform ocreae, adaxially glaucous leaves, longer bracts, shorter fruiting perianth, and achenes. (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. 570. | ||||||||||||||||
Parent taxa | Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Duravia | Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Duravia | ||||||||||||||||
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Subordinate taxa | ||||||||||||||||||
Synonyms | P. intermedium, P. douglasii subsp. nuttallii | |||||||||||||||||
Name authority | Meisner: in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 14: 101. (1856) | Small: Mongr. Amer. Sp. Polygonum, 132, plate 53. (1895) | ||||||||||||||||
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