Polygonum aviculare subsp. boreale

(Lange) Karlsson

Svensk Bot. Tidskr. 91: 249. 1998.

Common names: Northern knotweed
Weedy
Basionym: Polygonum aviculare var. boreale Lange Consp. Fl. Groenland. 1: 105. 1880
Synonyms: Polygonum arenastrum subsp. boreale (Lange) Á. Löve Polygonum boreale Lindman Polygonum heterophyllum subsp. boreale (Lange) Á. Löve & D. Löve
Treatment appears in FNA Volume 5. Treatment on page 557. Mentioned on page 556.

Plants green, homophyllous or subheterophyllous. Stems 1–7, prostrate to ascending, mostly branching from base, 6–50 (–90) cm. Leaves: ocrea 3.5–7 mm, proximal part cylindric to funnelform, distal part soon disintegrating, nearly completely deciduous; petiole 7–9 mm; blade green, lateral-veins visible but not raised abaxially, obovate-spatulate or oblanceolate, (12.5–) 16–44 (–55) × (4–) 6–18 (–22) mm, 2–4 (–5.5) times as long as wide, apex obtuse to rounded; stem-leaves (1.1–) 1.3–2.5 (–3) times as long as branch leaves. Cymes uniformly distributed, rarely crowded at tips of stems and branches, (3–) 4–7-flowered. Pedicels mostly exserted from ocreae, 2–5 mm. Flowers: perianth 3.3–5.5 mm, 1.6–2.8 times as long as wide; tube 25–35 (–39) % of perianth length; tepals overlapping, green with white or pink margins, obovate, flat or curved outward in fruit, outer tepals not pouched at base; veins branched, thickened; stamens 6–8. Achenes enclosed in perianth, dark-brown, ovate, 3-gonous, (2.5–) 2.7–4 (–4.2) mm, faces subequal, concave, apex straight, coarsely striate-tubercled; late-season achenes uncommon, 4–5 mm. 2n = 40.


Phenology: Flowering Aug–Oct.
Habitat: Sandy, gravelly, or rocky coastal areas
Elevation: 0-500 m

Distribution

V5 1138-distribution-map.gif

Greenland, Nfld. and Labr. (Labr.), nw Europe

Discussion

Selected References

None.

Lower Taxa

None.

"/2" is not declared as a valid unit of measurement for this property.

0.4 cm4 mm <br />0.004 m <br /> (0.42 cm4.2 mm <br />0.0042 m <br />) +
exserted +  and included +
dull +  and shiny +
smooth;roughened +
3-gonous +  and ovate +
whitish yellow +
elliptic +  and oblong +
striate-tubercled +
straight +
obtuse;rounded +
Mihai Costea +, François J. Tardif +  and Harold R. Hinds† +
(Lange) Karlsson +
not stipelike +
Polygonum aviculare var. boreale +
5 cm50 mm <br />0.05 m <br /> (6 cm60 mm <br />0.06 m <br />) +
0.6 cm6 mm <br />0.006 m <br /> (5 cm50 mm <br />0.05 m <br />) +
spatulate;obovate;spatulate;obovate;elliptic;lanceolate;elliptic +
coriaceous +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (2.2 cm22 mm <br />0.022 m <br />) +
foliaceous +  and perfoliate +
scale-like +
just below the soil surface or and above the soil surface +  and spreading +
Northern knotweed +
(3-)4-7-flowered +
crowded +  and distributed +
hyaline +  and silvery +
Greenland +, Nfld. and Labr. (Labr.) +  and nw Europe +
tubercled +  and striate-tubercled +
concave +
0-500 m +
concave +
subequal +
persistent +
adnate +, free +  and distinct +
disarticulating +  and solid +
decumbent to erect +  and prostrate +
unwinged +  and winged +
black +, red +, brown +  and yellowish +
exserted +  and included +
pubescent +  and glabrous +
spheroidal +, 4-gonous +, lenticular +, biconvex +, discoid +, 3-gonous +  and 2-gonous +
Sandy, gravelly, or rocky coastal areas +
compound +, branched +  and simple +
nonmembranous +
0.4 cm4 mm <br />0.004 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
sessile +  and petiolate +
deciduous +
pink +  and white +
pubescent +  and glabrous +
lobed +, undulate +, crisped +, crenulate +  and entire +
unbranched +  and branched +
not +  and thickened +
swollen +
silvery +, white +  and hyaline +
disintegrating +
deciduous +  and persistent +
0.35 cm3.5 mm <br />0.0035 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
coriaceous +  and membranous +
somewhat larger +
anatropous +, , +  and orthotropous +
erect;spreading +
accrescent +
0.2 cm2 mm <br />0.002 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
spreading;erect +
greenish white;pink +
campanulate +  and urceolate +
nonaccrescent +
0.33 cm3.3 mm <br />0.0033 m <br /> (0.55 cm5.5 mm <br />0.0055 m <br />) +
fleshy +, indurate +  and membranous +
0.7 cm7 mm <br />0.007 m <br /> (0.9 cm9 mm <br />0.009 m <br />) +
Flowering Aug–Oct. +
(2-)3(-4)-carpellate +
Svensk Bot. Tidskr. +
slender;stout +
woody +  and fibrous +
6 +  and 8 +
(1.1-)1.3-2.5(-3) times as long as branch leaves +
50 cm500 mm <br />0.5 m <br /> (90 cm900 mm <br />0.9 m <br />) +
flexuous +
prostrate +  and ascending +
1 +  and 7 +
papillous-scabridulous +
6 cm60 mm <br />0.06 m <br /> (50 cm500 mm <br />0.5 m <br />) +
2 +  and 3 +
penicillate +, fimbriate +  and capitate +
deciduous +  and persistent +
2-lobed +  and cylindric +
coriaceous +  and membranous +
connate +  and distinct +
spreading;erect +
Polygonum arenastrum subsp. boreale +, Polygonum boreale +  and Polygonum heterophyllum subsp. boreale +
Polygonum aviculare subsp. boreale +
Polygonum aviculare +
subspecies +
overlapping +
connate +  and distinct +
obovate +
coriaceous +
persistent +
membranous +
pubescent +  and glabrous +
subheterophyllous +  and homophyllous +
not cushionlike +