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beak-seed knotweed, Blake's knotweed, leathery knotweed, renouée coriace, striate knotweed

Parry's knotweed, Parry's or prickly knotweed, prickly knotweed

Habit Plants light green (often covered with whitish powdery mildew), homophyllous or, sometimes, heterophyllous. Herbs, compact, often cushion-like.
Stems

erect when young, decumbent or prostrate later, moderately branched especially from base, not wiry, 50–70 cm.

erect, green-brown, simple or branched from base, not wiry, 2–5(–8) cm, glabrous.

Leaves

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.

± 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.

Inflorescences

axillary, cymes in axils of most leaves and toward tips of stems and branchs, 1–3(–5)-flowered.

axillary;

cymes in most axils, 1-flowered.

Pedicels

enclosed in ocreae, 1.3–1.8(–2) mm.

absent.

Flowers

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.

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.

Achenes

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.

slightly exserted from perianth at maturity, dark brown, ovate, 1.2–1.6(–2) mm, faces subequal, shiny, smooth.

2n

= 40, 60.

Polygonum achoreum

Polygonum parryi

Phenology Flowering Jul–Sep. Flowering May–July.
Habitat Disturbed areas, roadsides, sidewalks, edges of cultivated fields Vernally moist, open, sandy or rocky places
Elevation 10-800 m (0-2600 ft) 500-2000 m (1600-6600 ft)
Distribution
from FNA
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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[BONAP county map]
from FNA
CA; WA
[WildflowerSearch map]
[BONAP county map]
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.)

Source FNA vol. 5, p. 551. FNA vol. 5, p. 563.
Parent taxa Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Polygonum Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Duravia
Sibling taxa
P. argyrocoleon, P. austiniae, P. aviculare, P. bidwelliae, P. bolanderi, P. californicum, P. cascadense, P. douglasii, P. engelmannii, P. erectum, P. fowleri, P. glaucum, P. heterosepalum, P. hickmanii, P. humifusum, P. majus, P. marinense, P. minimum, P. nuttallii, P. oxyspermum, P. paronychia, P. parryi, P. patulum, P. plebeium, P. polygaloides, P. ramosissimum, P. sawatchense, P. shastense, P. spergulariiforme, P. striatulum, P. tenue, P. utahense
P. achoreum, P. argyrocoleon, P. austiniae, P. aviculare, P. bidwelliae, P. bolanderi, P. californicum, P. cascadense, P. douglasii, P. engelmannii, P. erectum, P. fowleri, P. glaucum, P. heterosepalum, P. hickmanii, P. humifusum, P. majus, P. marinense, P. minimum, P. nuttallii, P. oxyspermum, P. paronychia, P. patulum, P. plebeium, P. polygaloides, P. ramosissimum, P. sawatchense, P. shastense, P. spergulariiforme, P. striatulum, P. tenue, P. utahense
Synonyms P. erectum subsp. achoreum
Name authority S. F. Blake: Rhodora 19: 232. (1917) Greene: Bull. Torrey Bot. Club 8: 99. (1881)
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