Polygonum polygaloides
Polygonum
close-flower knotweed, close-flower knotweed (ssp. confertiflorum), Kellogg's knotweed (ssp. kelloggii), milkwort knotweed, polygala knotweed, whitemargin knotweed
doorweed, knotweed, smartweed
erect, green, usually divaricately branched, rarely simple, ± wiry, (2–)6–20(–25) cm, glabrous.
prostrate to erect, glabrous, smooth or sometimes papillous-scabridulous.
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.
cauline, alternate (opposite in P. humifusum), petiolate or sessile;
ocrea with distal part persistent, often hyaline, white or silvery, 2-lobed, chartaceous, glabrous, disintegrating into fibers, or disintegrating completely;
petiole base articulated with ocrea or not;
blade linear, lanceolate, elliptic, ovate, or subround, margins entire.
axillary and terminal, spikelike, subglobose to cylindric;
cymes in most axils or crowded distally, 1–3-flowered.
axillary or axillary and terminal, spikelike, or flowers solitary;
peduncle absent.
enclosed in ocreae, erect, 0.1–2 mm, sometimes absent.
present or absent.
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.
bisexual, 1–7(–10) per ocreate fascicle, base not stipelike;
perianth nonaccrescent, white or greenish white to pink, campanulate to urceolate, glabrous;
tepals 5, connate 3–70% of their length, petaloid or sepaloid, monomorphic or, rarely, dimorphic, the inner usually flat, the outer flat or sometimes keeled and cucullate distally, sometimes of different length than the inner;
stamens 3–8 (some may be reduced to staminodes);
filaments distinct, free or adnate to perianth tube, glabrous;
anthers whitish yellow, pink to purple or orange-pink, elliptic to oblong;
styles (2–)3, mostly spreading, distinct or connate proximally;
stigmas 2–3, capitate.
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.
included or exserted, yellow-green, brown, or black, unwinged, (2–)3-gonous, glabrous.
embryo curved.
= 10.
Polygonum polygaloides
Polygonum
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.)
Species ca. 65 (33 in the flora).
Two sections of Polygonum are recognized here. Section Polygonum is nearly cosmopolitan and best represented in north-temperate regions; sect. Duravia comprises species restricted to North America. K. Haraldson (1978) recognized both sections based on differences in stem morphology, petiole structure, and pollen morphology. J. C. Hickman (1984) described sect. Monticola and included in it species of sect. Duravia occurring mostly in montane habitats, with leaves articulated to the ocreae, one-veined, and not mucronate, proximal leaves lanceolate to round, and styles connate at their bases and neither hardened nor persistent. L.-P. Ronse Decraene and J. R. Akeroyd (1988) and L.-P. Ronse Decraene et al. (2000) included sect. Duravia in sect. Polygonum based on floral and fruit characters.
Similarities in floral structure, fruit anatomy, and pollen morphology have been noted between Polygonella with Polygonum (L.-P. Ronse Decraene et al. 2000). Based on evidence from comparative morphological studies, Ronse Decraene et al. (2004) included Polygonella in sect. Duravia of Polygonum.
Four introduced taxa of sect. Polygonum that were collected in the flora area at the end of the nineteenth century and beginning of the twentieth century appear not to have persisted here and are not included in the keys. Polygonum arenarium Waldstein & Kitaibel and P. bellardii Allioni were reported by B. L. Robinson (1902) from Rhode Island and Massachusetts, respectively. The former resembles P. patulum but has open flowers. Polygonum bellardii is discussed below under P. ramosissimum. Polygonum polycnemoides Jaubert & Spach and P. humifusum C. Merck ex K. Koch subsp. humifusum were reported by J. F. Brenckle (1941). The former was collected in New York City in 1894 and in Idaho in 1940. It differs from all other Polygonum species in having a tube 55–70% of the perianth length. Polygonum humifusum subsp. humifusum is discussed below under P. humifusum subsp. caurianum.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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 |
Key to the Sections of Polygonum
1. Stems distinctly and ± regularly 8-16-ribbed; leaf blade venation pinnate, secondary veins conspicuous; anthers whitish yellow; nearly worldwide | sect. Polygonum |
1. Stems 4-gonous, ribs obscure or absent; leaf blade venation parallel, secondary veins not conspicuous; anthers pink to purple; mostly w North America | sect. Duravia |
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OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
PNW Herbaria, Turner Photog. 
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