Page authors: Don Knoke, David Giblin
Cyclachaena xanthiifolia
carelessweed, burweed marsh-elder, tall marsh-elder

Distribution: Ocurring east of the Cascades crest in Washington; British Columbia to California, east across much of North America to the Atlantic Coast.

Habitat: Bottomlands and other moist, open, often disturbed areas.

Flowers: August-October

Origin: Introduced from south-central Canada and the central U.S.

Growth Duration: Annual

Conservation Status: Not of concern

Pollination: Bees, flies, beetles, wasps


Large, coarse annual up to 20 dm. tall.


Leaves long-petiolate, the blade broadly ovate, 5-20 cm. long and 2.5-20 cm. wide, coarsely and often doubly serrate, gradually reduced upward.


Heads numerous, nearly sessile, in a large, paniculiform inflorescence; involucre 1.5-3 mm. high, the 5 herbaceous outer bracts larger than the 5 membranous inner bracts; corollas of the pistillate flowers obsolete; staminate corollas tubular, greenish, with undivided style, the filaments attached to each other; receptacle small, chaffy throughout; pappus none.


Achenes compressed parallel to the involucral bracts.

Accepted Name:
Cyclachaena xanthiifolia (Nutt.) Fresenius
Publication: Index Seminum (Frankfurt). 1836: 4. 1836.

Synonyms & Misapplications:
Iva xanthifolia Nutt. [HC]
Iva xanthiifolia Nutt.
Additional Resources:

PNW Herbaria: Specimen records of Cyclachaena xanthiifolia in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Cyclachaena xanthiifolia checklist entry.

OregonFlora: Cyclachaena xanthiifolia information.

E-Flora BC: Cyclachaena xanthiifolia atlas page.

CalPhotos: Cyclachaena xanthiifolia photos.

USDA Plants: Cyclachaena xanthiifolia information.

16 photographs:
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