Polygonum fowleri subsp. hudsonianum

(S. J. Wolf & McNeill) Costea & Tardif

Sida 20: 994. 2003.

Common names: Hudsonian knotweed renouée de la baie d’Hudson
Endemic
Basionym: Polygonum caurianum subsp. hudsonianum S. J. Wolf & McNeill Rhodora 88: 469, fig. 3. 1986
Synonyms: Polygonum hudsonianum (S. J. Wolf & McNeill) H. R. Hinds
Treatment appears in FNA Volume 5. Treatment on page 555.

Plants often purplish tinged, homophyllous, rarely subsucculent. Stems prostrate, 5–30 cm. Leaves: ocrea 2.5–5 mm; petiole 2–5 mm; blade purple tinged, narrowly obovate or oblanceolate, 8–30 × 4–12(–15) mm, apex rounded to obtuse; middle stem leaves 1.1–1.8(–2.2) times as long as adjacent branch leaves. Cymes 2–7(–10)-flowered. Pedicels 1–1.5 mm. Perianths (2.2–)2.5–3.3(–3.5) mm. Achenes ovate-lanceolate, (2–)3-gonous, (1.8–)2–2.5(–3.1) mm, faces often unequal, ± flat to concave, roughened, rarely obscurely tubercled.


Phenology: Flowering Jul–Sep.
Habitat: Gravelly seashores
Elevation: 0-30 m

Distribution

V5 1132-distribution-map.gif

Man., Nfld. and Labr., N.W.T., N.S., Nunavut, Ont., Que.

Discussion

Wolf and McNeill described Hudsonian knotweed as a subspecies of Polygonum caurianum (P. humifusum subsp. caurianum in this treatment). In raising it to the rank of species, H. R. Hinds (1995) noted that “separation between P. fowleri and P. hudsonianum, however, is more difficult.” M. Costea and F. J. Tardif (2003) concluded that the taxon is best treated as a subspecies of P. fowleri, based on the existence of intermediate plants.

Selected References

None.

Lower Taxa

None.
Mihai Costea +, François J. Tardif +  and Harold R. Hinds† +
(S. J. Wolf & McNeill) Costea & Tardif +
Polygonum caurianum subsp. hudsonianum +
Hudsonian knotweed +  and renouée de la baie d’Hudson +
Man. +, Nfld. and Labr. +, N.W.T. +, N.S. +, Nunavut +, Ont. +  and Que. +
0-30 m +
Gravelly seashores +
Flowering Jul–Sep. +
Polygonum hudsonianum +
Polygonum fowleri subsp. hudsonianum +
Polygonum fowleri +
subspecies +