Page author: David Giblin
Lycopus asper
rough water-horehound

Distribution: Chiefly east of the Cascades; southern British Columbia to California, east to Colorado and Minnisota.

Habitat: Marshes and shores of streams and lakes; tolerant of alkali.

Flowers: June-August

Origin: Native

Growth Duration: Perennial

Conservation Status: Not of concern


Perennial herbs from tuberous rhizomes, the simple or branched, square stem 2-8 dm. tall, with spreading hairs on the angles.


Leaves opposite, all cauline, glabrous or scabrous above and glabrous below, numerous, 3.5-10 cm. long and 0.6-3.5 cm. broad, oblong-lanceolate, coarsely and evenly serrate, nearly sessile.


Flowers sessile, verticillate in the axils of scarcely reduced leaves; calyx with 5 firm, narrow, sharp-pointed lobes; corolla white, 3-5 mm. long, about equally 4-lobed; fertile stamens 2, barely exerted, sterile stamens 2, small, club-shaped; style 2-parted; ovary 2-celled, superior.


Nutlets 4, the outer apical margin truncate and irregularly toothed.

Accepted Name:
Lycopus asper Greene
Publication: Pittonia 3(19C): 339. 1898.

Synonyms & Misapplications:
(none provided)
Additional Resources:

PNW Herbaria: Specimen records of Lycopus asper in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Lycopus asper checklist entry.

E-Flora BC: Lycopus asper atlas page.

CalPhotos: Lycopus asper photos.

USDA Plants: Lycopus asper information.

16 photographs:
Group by