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

close-flower knotweed, close-flower knotweed (ssp. confertiflorum), Kellogg's knotweed (ssp. kelloggii), milkwort knotweed, polygala knotweed, whitemargin knotweed

Habit Shrubs or subshrubs. Herbs.
Stems

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

erect, green, usually divaricately branched, rarely simple, ± wiry, (2–)6–20(–25) 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, 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.

Inflorescences

axillary;

cymes crowded in distal axils, 2–5-flowered.

axillary and terminal, spikelike, subglobose to cylindric;

cymes in most axils or crowded distally, 1–3-flowered.

Pedicels

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

enclosed in ocreae, erect, 0.1–2 mm, sometimes absent.

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.

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.

Achenes

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

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.

Polygonum paronychia

Polygonum polygaloides

Phenology Flowering Mar–Sep.
Habitat Coastal sands, scrub along coast
Elevation 0-50 m (0-200 ft)
Distribution
from FNA
CA; OR; WA; BC
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CA; CO; ID; MT; NM; NV; OR; UT; WA; WY; AB; BC; SK
[WildflowerSearch map]
[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.)

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.)

Key
1. Margins of bracts green, if white then scarious border less than 0.2 mm wide
→ 2
1. Margins of bracts white, scarious border (0.2-)0.25-1 mm wide
→ 3
2. Achenes lanceolate, 2-2.5 mm; bracts elliptic-lanceolate, appressed, rigid; stamens 5-8
subsp. esotericum
2. Achenes ovate, 1.3-1.7 mm; bracts linear to linear-lanceolate, ± patent, soft; stamens 3
subsp. kelloggii
3. Inflorescences narrowly cylindric, continuous from bases of branches or stems; achenes 2-2.5 mm, lanceolate
subsp. esotericum
3. Inflorescences round to ovate or cylindric, confined to tips of branches, rarely continuous from bases of branches or stems; achenes 1.3-2.1 mm, ovate-lanceolate to ovate
→ 4
4. Inflorescences round to ovate; scarious borders of bracts 0.5-1 mm wide; stamens8
subsp. polygaloides
4. Inflorescences ovate to cylindric; scarious borders of bracts 0.25-0.4 mm wide; stamens 3
subsp. confertiflorum
Source FNA vol. 5, p. 562. FNA vol. 5, p. 565.
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. heterosepalum, P. hickmanii, P. humifusum, P. majus, P. marinense, P. minimum, P. nuttallii, P. oxyspermum, P. paronychia, P. parryi, P. patulum, P. plebeium, P. ramosissimum, P. sawatchense, P. shastense, P. spergulariiforme, P. striatulum, P. tenue, P. utahense
Subordinate taxa
P. polygaloides subsp. confertiflorum, P. polygaloides subsp. esotericum, P. polygaloides subsp. kelloggii, P. polygaloides subsp. polygaloides
Name authority Chamisso & Schlechtendal: Linnaea 3: 51. (1828) Meisner: in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 14: 101. (1856)
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