Polygonum polygaloides |
Polygonum achoreum |
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close-flower knotweed, close-flower knotweed (ssp. confertiflorum), Kellogg's knotweed (ssp. kelloggii), milkwort knotweed, polygala knotweed, whitemargin knotweed |
beak-seed knotweed, Blake's knotweed, leathery knotweed, renouée coriace, striate knotweed |
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Habit | Herbs. | Plants light green (often covered with whitish powdery mildew), homophyllous or, sometimes, heterophyllous. | ||||||||||||||||
Stems | erect, green, usually divaricately branched, rarely simple, ± wiry, (2–)6–20(–25) cm, glabrous. |
erect when young, decumbent or prostrate later, moderately branched especially from base, not wiry, 50–70 cm. |
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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. |
ocreae 5–12 mm, proximal part cylindric, distal part soon disintegrating into brown fibers; petiole 0.3–1.5 mm; blade light yellowish green, elliptic to obovate, 8–35 × 3–15 mm, margins flat, apex rounded; stem leaves 1–2.1(–3) times longer than branch leaves; distal leaves overtopping flowers. |
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Inflorescences | axillary and terminal, spikelike, subglobose to cylindric; cymes in most axils or crowded distally, 1–3-flowered. |
axillary, cymes in axils of most leaves and toward tips of stems and branchs, 1–3(–5)-flowered. |
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Pedicels | enclosed in ocreae, erect, 0.1–2 mm, sometimes absent. |
enclosed in ocreae, 1.3–1.8(–2) 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. |
closed; perianth 2.6–4 mm; tube 40–55% of perianth length; tepals incurved, yellow-green with yellow to green, rarely pinkish, margins, sepaloid, ± keeled, narrowly oblong, cucullate; midveins unbranched, moderately to heavily thickened, tepals appearing keeled; stamens 5–8. |
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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, yellow-green to tan, ovate, 3-gonous, 2.4–3.5 mm, faces unequal, apex not beaked, edges concave or nearly straight, dull, uniformly tubercled; late-season achenes common, 3–5 mm. |
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2n | = 40, 60. |
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Polygonum polygaloides |
Polygonum achoreum |
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Phenology | Flowering Jul–Sep. | |||||||||||||||||
Habitat | Disturbed areas, roadsides, sidewalks, edges of cultivated fields | |||||||||||||||||
Elevation | 10-800 m (0-2600 ft) | |||||||||||||||||
Distribution |
AZ; CA; CO; ID; MT; NM; NV; OR; UT; WA; WY; AB; BC; SK
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AK; CO; CT; IA; ID; IL; IN; KS; ME; MI; MN; MO; MT; ND; NE; NV; NY; OH; OR; SD; UT; VT; WA; WI; WV; WY; AB; BC; MB; NB; NS; NT; ON; QC; SK; YT
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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.) |
Polygonum achoreum frequently is confused with P. erectum. It can be distinguished by its usually homophyllous leaves, its perianth, which is enlarged at the base and constricted above the fruit, its longer perianth tube, and its yellow-green to tan, tubercled 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. 551. | ||||||||||||||||
Parent taxa | Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Duravia | Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Polygonum | ||||||||||||||||
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Subordinate taxa | ||||||||||||||||||
Synonyms | P. erectum subsp. achoreum | |||||||||||||||||
Name authority | Meisner: in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 14: 101. (1856) | S. F. Blake: Rhodora 19: 232. (1917) | ||||||||||||||||
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