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beach knotweed, beach or black or dune knotweed, black knotweed, dune knotweed

dwarf desert knotweed, odd-sepal knotweed

Habit Shrubs or subshrubs. Herbs, compact, often cushion-like.
Stems

prostrate or ascending, brown, branched, rooting at nodes, not wiry, 10–100 cm, glabrous, covered with remains of lacerate, hyaline ocreae.

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

Leaves

crowded at branch tips, articulated to ocreae, basal leaves caducous or persistent, distal leaves not reduced in size;

ocrea 15–20 mm, glabrous, proximal part cylindric to funnelform, distal part silvery, entire or slightly lacerate, disintegrating into persistent white-gray curly fibers;

petiole 0–0.5 mm;

blade 1-veined, without pleats, linear to oblanceolate, (5–)10–20(–33) × 3–8 mm, coriaceous, margins revolute, smooth, apex acute or mucronate.

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 crowded in distal axils, 2–5-flowered.

axillary;

cymes in most axils, 2–3-flowered.

Pedicels

enclosed in ocreae, erect to spreading, 2–5 mm.

enclosed in ocreae, erect, 0.1–1 mm.

Flowers

semi-open or open;

perianth (4.5–)6–10 mm;

tube 22–48% of perianth length;

tepals partially overlapping, uniformly pink or white, reddish brown when dried, petaloid, oblong-ovate to ± lanceolate, apex rounded;

midveins pinnately branched;

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

enclosed in or slightly exserted from perianth, black, ovate, 4–5 mm, faces subequal, shiny, smooth.

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

Polygonum paronychia

Polygonum heterosepalum

Phenology Flowering Mar–Sep. Flowering Jun–Aug.
Habitat Coastal sands, scrub along coast Dry waste ground, open flats in sagebrush plains, ponderosa pine forests
Elevation 0-50 m (0-200 ft) 1000-1500 m (3300-4900 ft)
Distribution
from FNA
CA; OR; WA; BC
[WildflowerSearch map]
[BONAP county map]
from FNA
ID; NV; OR
[BONAP county map]
Discussion

Polygonum paronychia may be cultivated in rock gardens in open sites with sandy soil.

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

Of conservation concern.

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

Source FNA vol. 5, p. 562. 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. 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. 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 Chamisso & Schlechtendal: Linnaea 3: 51. (1828) M. Peck & Ownbey: Madroño 10: 250. (1950)
Web links