Polygonum douglasii

Greene

Bull. Calif. Acad. Sci. 1: 125. 1885.

Common names: Douglas’s knotweed renouée de Douglas
WeedyIllustratedEndemic
Synonyms: Polygonum douglasii var. latifolium (Engelmann) Greene Polygonum emaciatum (Small) Greene Polygonum montanum Michaux Polygonum tenue var. commune Engelmann Polygonum tenue var. latifolium Engelmann
Treatment appears in FNA Volume 5. Treatment on page 567. Mentioned on page 562, 568.

Herbs. Stems erect, green, simple or branched, not wiry, 5–80 cm, glabrous or sparsely papillose-scabridulous. Leaves uniformly distributed, articulated to ocreae, basal leaves caducous, distal leaves abruptly reduced to bracts; ocrea 6–12 mm, glabrous or minutely papillose-scabridulous, proximal part cylindric, distal part hyaline, lacerate; petiole 0.1–2 mm; blade 1-veined, not pleated, linear, narrow-oblong, or oblanceolate, 15–55 × 2–8 (–12) mm, margins revolute, smooth or papillose-denticulate; apex acute to mucronate. Inflorescences axillary and terminal, spikelike, elongate; cymes widely spaced along branches, 2–4-flowered. Pedicels mostly exserted from ocreae, reflexed, 2–6 mm. Flowers closed; perianth 3–4.5 mm; tube 20–28% of perianth length; tepals overlapping, green to tannish with white or pink margins, petaloid, oblong, cucullate, navicular, apex rounded; midveins usually branched, rarely unbranched; stamens 8. Achenes enclosed in perianth, black, elliptic or oblong to ovate, 3–4 (–4.5) mm, faces subequal, shiny or dull, smooth or minutely striate-tubercled.


Phenology: Flowering Jun–Oct.
Habitat: Dry, often disturbed places, rock outcrops, sandy ground
Elevation: 300-3000 m

Distribution

V5 1160-distribution-map.gif

Alta., B.C., Man., Ont., Que., Sask., Yukon, Ariz., Calif., Colo., Idaho, Iowa, Mich., Minn., Mont., Nebr., Nev., N.H., N.Mex., N.Y., Oreg., S.Dak., Utah, Vt., Va., Wash., Wyo.

Discussion

Five taxa that have been included in Polygonum douglasii (E. Murray 1982; J. C. Hickman 1984; J. T. Kartesz and K. N. Gandhi 1990) are treated here as distinct species: P. austiniae, P. majus, P. nuttallii, P. sawatchense, and P. spergulariiforme. Hickman noted extensive intergradation and numerous intermediate specimens among those sympatric elements, but qualitative or quantitative characters allow reliable discrimination in most cases (M. Costea and F. J. Tardif 2005), and species are here circumscribed similar to C. L. Hitchcock (1964).

Greene described var. latifolium as having leaf blades and achenes broader than those of var. douglasii. C. L. Hitchcock (1964) recognized the former, but the characters used to distinguish it appear to vary continuously, and reliable separation is not possible.

Selected References

None.

Lower Taxa

None.

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

... more about "Polygonum douglasii"
reticulate +, tubercled +  and smooth +
0.4 cm4 mm <br />0.004 m <br /> (0.45 cm4.5 mm <br />0.0045 m <br />) +
exserted +  and included +
dull +  and shiny +
oblong +  and ovate +
pink +  and purple +
elliptic +  and oblong +
rounded;acute;mucronate +
Mihai Costea +, François J. Tardif +  and Harold R. Hinds† +
Greene +
not stipelike +
0.8 cm8 mm <br />0.008 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
1.5 cm15 mm <br />0.015 m <br /> (5.5 cm55 mm <br />0.055 m <br />) +
oblanceolate;narrow-oblong;oblanceolate;narrow-oblong;linear;not pleated +
coriaceous +
0.2 cm2 mm <br />0.002 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
foliaceous +  and perfoliate +
scale-like +
just below the soil surface or and above the soil surface +  and spreading +
Douglas’s knotweed +  and renouée de Douglas +
2-4-flowered +
Alta. +, B.C. +, Man. +, Ont. +, Que. +, Sask. +, Yukon +, Ariz. +, Calif. +, Colo. +, Idaho +, Iowa +, Mich. +, Minn. +, Mont. +, Nebr. +, Nev. +, N.H. +, N.Mex. +, N.Y. +, Oreg. +, S.Dak. +, Utah +, Vt. +, Va. +, Wash. +  and Wyo. +
300-3000 m +
striate-tubercled +  and smooth +
dull +  and shiny +
subequal +
adnate +, free +  and distinct +
semi-open +  and open +
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 +
Dry, often disturbed places, rock outcrops, sandy ground +
compound +, branched +  and simple +
elongate +  and spikelike +
nonmembranous +
articulated +
distributed +
deciduous +
pink +  and white +
not rugulose +
papillose-denticulate +
unbranched +  and branched +
swollen +
silvery +, white +  and hyaline +
disintegrating +
deciduous +  and persistent +
papillose-scabridulous +
0.6 cm6 mm <br />0.006 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
coriaceous +  and membranous +
somewhat larger +
anatropous +, , +  and orthotropous +
accrescent +
0.2 cm2 mm <br />0.002 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
spreading;erect +
greenish white;pink +
campanulate +  and urceolate +
nonaccrescent +
0.3 cm3 mm <br />0.003 m <br /> (0.45 cm4.5 mm <br />0.0045 m <br />) +
fleshy +, indurate +  and membranous +
not +  and articulated +
0.01 cm0.1 mm <br />1.0e-4 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
Flowering Jun–Oct. +
(2-)3(-4)-carpellate +
Bull. Calif. Acad. Sci. +
papillose-scabridulous +  and smooth +
slender;stout +
woody +  and fibrous +
Weedy +, Illustrated +  and Endemic +
not wiry +, branched +  and simple +
zigzagged +  and straight +
papillose-scabridulous +
4-gonous +
5 cm50 mm <br />0.05 m <br /> (80 cm800 mm <br />0.8 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 douglasii var. latifolium +, Polygonum emaciatum +, Polygonum montanum +, Polygonum tenue var. commune +  and Polygonum tenue var. latifolium +
Polygonum douglasii +
Polygonum sect. Duravia +
species +
overlapping +
green +  and tannish +
connate +  and distinct +
navicular +, cucullate +  and oblong +
coriaceous +
persistent +
membranous +
pubescent +  and glabrous +
heterophyllous +  and homophyllous +