Polygonum parryi |
Polygonum achoreum |
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Parry's knotweed, Parry's or prickly knotweed, prickly knotweed |
beak-seed knotweed, Blake's knotweed, leathery knotweed, renouée coriace, striate knotweed |
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Habit | Herbs, compact, often cushion-like. | Plants light green (often covered with whitish powdery mildew), homophyllous or, sometimes, heterophyllous. |
Stems | erect, green-brown, simple or branched from base, not wiry, 2–5(–8) cm, glabrous. |
erect when young, decumbent or prostrate later, moderately branched especially from base, not wiry, 50–70 cm. |
Leaves | ± uniformly distributed, dense, not articulated to ocreae, basal leaves ± persistent, distal leaves gradually reduced to bracts; ocrea 2–4(–5) mm, glabrous, proximal part cylindric, distal part deeply lacerate, disintegrating into white, curled fibers; petiole absent; blade 3-veined, without pleats, linear-lanceolate, subulate, 5–13(–20) × 0.4–1 mm, margins revolute, smooth, apex spine-tipped. |
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. |
Inflorescences | axillary; cymes in most axils, 1-flowered. |
axillary, cymes in axils of most leaves and toward tips of stems and branchs, 1–3(–5)-flowered. |
Pedicels | absent. |
enclosed in ocreae, 1.3–1.8(–2) mm. |
Flowers | closed; perianth 1.5–2(–2.5) mm; tube 6–15% of perianth length; tepals overlapping, usually reddish with white margins, petaloid, oblong, navicular, apex acute; midveins unbranched; stamens 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. |
Achenes | slightly exserted from perianth at maturity, dark brown, ovate, 1.2–1.6(–2) mm, faces subequal, shiny, smooth. |
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. |
2n | = 40, 60. |
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Polygonum parryi |
Polygonum achoreum |
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Phenology | Flowering May–July. | Flowering Jul–Sep. |
Habitat | Vernally moist, open, sandy or rocky places | Disturbed areas, roadsides, sidewalks, edges of cultivated fields |
Elevation | 500-2000 m (1600-6600 ft) | 10-800 m (0-2600 ft) |
Distribution |
CA; WA
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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 | 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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Source | FNA vol. 5, p. 563. | FNA vol. 5, p. 551. |
Parent taxa | Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Duravia | Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Polygonum |
Sibling taxa | ||
Synonyms | P. erectum subsp. achoreum | |
Name authority | Greene: Bull. Torrey Bot. Club 8: 99. (1881) | S. F. Blake: Rhodora 19: 232. (1917) |
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