Page author: David Giblin
Senecio hydrophilus
alkali marsh butterweed, water groundsel, alkali marsh ragwort

Distribution: Occurring east of the Cascades crest in Washington; British Columbia to California, east to the Rocky Mountains and northern Great Plains.

Habitat: Swampy places in the valleys and foothills; tolerant of alkali.

Flowers: June- September

Origin: Native

Growth Duration: Biennial, Perennial

Conservation Status: Not of concern

Pollination: Bumblebees, bees, butterflies, flies, beetles


Robust, more or less glaucous, glabrous, fibrous-rooted perennial, 4-20 dm. tall, the stems usually clustered.


Thick and firm, usually entire but occasionally toothed, the basal and lower cauline ones long-petiolate, the blade narrowly elliptic, 10-20 cm. long and 2-5 cm. wide; middle and upper leaves few, strongly reduced, becoming sessile on the upper stem.


Heads usually numerous and crowded; involucre 5-8 mm high, narrow, its bracts usually black-tipped; rays few, 4-8 mm. long, or wanting.

Accepted Name:
Senecio hydrophilus Nutt.
Publication: Trans. Amer. Philos. Soc., n. s. 7: 411. 1841.

Synonyms & Misapplications:
Senecio hydrophilus Nutt. var. pacifica Greene
Additional Resources:

PNW Herbaria: Specimen records of Senecio hydrophilus in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Senecio hydrophilus checklist entry.

OregonFlora: Senecio hydrophilus information.

E-Flora BC: Senecio hydrophilus atlas page.

CalPhotos: Senecio hydrophilus photos.

USDA Plants: Senecio hydrophilus information.

19 photographs:
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