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

dwarf desert knotweed, odd-sepal knotweed

Habit Herbs, compact, often cushion-like. Herbs, compact, often cushion-like.
Stems

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

erect, green or reddish, simple or branched near base, not wiry, 1.5–5 cm, glabrous.

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.

uniformly distributed, dense, not articulated to ocreae, basal leaves persistent or caducous, distal leaves gradually reduced to bracts;

ocrea 3–6 mm, glabrous, proximal part cylindric, distal part disintegrating almost to base, with whitish, straight, rigid fibers;

petiole absent;

blade 3-veined, without pleats, linear to lanceolate, 10–20 × 0.6–2.7 mm, margins revolute, smooth, apex spine-tipped.

Inflorescences

axillary;

cymes in most axils, 1-flowered.

axillary;

cymes in most axils, 2–3-flowered.

Pedicels

absent.

enclosed in ocreae, erect, 0.1–1 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 2.3–2.7 mm;

tube 3–7% of perianth length;

tepals overlapping, whitish with whitish or pink margins, petaloid, oblong, navicular, dimorphic, outer 2 shorter than inner 3, outer 2 0.8–1.2 mm, inner 2.3–2.7 mm, papillose at base, apex acute or acuminate;

midveins unbranched;

stamens 5–6.

Achenes

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

enclosed in perianth, olive brown, narrowly ovate to ovate-lanceolate, 1.5–2 mm, faces subequal, shiny, smooth.

Polygonum parryi

Polygonum heterosepalum

Phenology Flowering May–July. Flowering Jun–Aug.
Habitat Vernally moist, open, sandy or rocky places Dry waste ground, open flats in sagebrush plains, ponderosa pine forests
Elevation 500-2000 m (1600-6600 ft) 1000-1500 m (3300-4900 ft)
Distribution
from FNA
CA; WA
[WildflowerSearch map]
[BONAP county map]
from FNA
ID; NV; OR
[BONAP county map]
Discussion

Of conservation concern.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 5, p. 563. FNA vol. 5, p. 563.
Parent taxa Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Duravia Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Duravia
Sibling taxa
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
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. 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
Name authority Greene: Bull. Torrey Bot. Club 8: 99. (1881) M. Peck & Ownbey: Madroño 10: 250. (1950)
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