Persicaria hydropiper
smartweed, mild water-pepper

Distribution: Introduced weed found in much of North America and throughout the Pacific Northwest.

Habitat: Swamps, ditches, and other wet places, mostly at low elevations.

Flowers: July - September

Origin: Introduced

Conservation Status: Not of concern


Mostly glabrous annual, the stems rooting at the nodes, the upright stems simple to freely branched, peppery to the taste, the herbage with glands in small pits.


Leaves alternate, numerous, all cauline, only slightly reduced upward, the blades lanceolate to elliptic-lanceolate, 5-7 cm. long, the stipules up to 15 mm. long, oblique.


Inflorescence a terminal raceme and several lateral, spike-like, interrupted, lateral racemes 2-7 cm. long; pedicles 1-2 mm. long; perianth 3-4 mm. long, glandular, attached to about mid-length, the 4 segments greenish with white or pink margins, oblong; stamens 4 or 6; styles 2 or 3, distinct.


Achenes brown, 3 mm. long.

Accepted Name:
Persicaria hydropiper (L.) Spach
Publication: Hist. Nat. Vég. 10: 536. 1841. 1841.

Synonyms & Misapplications:
Polygonum hydropiper L. [HC]
Polygonum hydropiper L. var. projectum Stanford
Additional Resources:

PNW Herbaria: Specimen records of Persicaria hydropiper in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Persicaria hydropiper checklist entry.

OregonFlora: Persicaria hydropiper information.

E-Flora BC: Persicaria hydropiper atlas page.

CalPhotos: Persicaria hydropiper photos.

USDA Plants: Persicaria hydropiper information.

17 photographs:
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