Page authors: Don Knoke, David Giblin
Polygonum fowleri
Fowler's knotweed

Distribution: Occurring west of the Cascades in Washington; Alaska south to California, east across northern Canada to northeastern North America.

Habitat: Coastal salt marshes.

Flowers: July-November

Origin: Native

Conservation Status: Not of concern


Very leafy annual or biennial, the stems prostrate or spreading, freely branched, 1-3 dm. long.


Leaves alternate, usually overlapping, gradually reduced upward, the short petiole jointed; leaf blades elliptic-linear to elliptic-oblanceolate, rounded, 1.5-3 cm. long and 3-10 mm. wide, firm; stipules sheathing, lacerate, 3-6 mm. long.


Flowers in closely packed, short, few-flowered, axillary racemes, exceeded by the bracts; pedicles 1-3 mm. long; the 5 perianth segments 3 mm. long, attached 1/3 their length, greenish with pink margins, oblong; styles 3, very short.

Identification Notes:

Achene 3-angled, lance-ovoid, olive green to yellowish-brown, smooth and shining.

Accepted Name:
Polygonum fowleri B.L. Rob.
Publication: Rhodora. 4: 67, plate 35, figs. 14, 15. 1902.

Synonyms & Misapplications:
(none provided)
ssp. fowleri – Fowler's knotweed
Additional Resources:

PNW Herbaria: Specimen records of Polygonum fowleri in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Polygonum fowleri checklist entry.

E-Flora BC: Polygonum fowleri atlas page.

CalPhotos: Polygonum fowleri photos.

USDA Plants: Polygonum fowleri information.

6 photographs:
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