Page author: David Giblin
Toxicodendron diversilobum
Pacific poison-oak

Distribution: Occurring chiefly west of the Cascades crest in Washington; British Columbia to California, east to Nevada.

Habitat: Open woods at low elevations.

Flowers: April-July

Origin: Native

Growth Duration: Perennial

Conservation Status: Not of concern

Pollination: Bees


Glabrous to pubescent shrubs or climbing vines 1-15 m. tall.


Leaves trifoliate; leaflets ovate to obovate, sinuate to deeply lobed, rounded to acute, 3-7 cm. long.


Inflorescence of loose, axillary panicles; flowers mostly imperfect, dioecious, 1-2 mm. long; calyx 5-parted, pubescent to glabrous, about half the length of the petals; petals 5, spreading; staminate flowers with 5 exerted stamens, the filaments attached to the rim of a fleshy, flat disk; ovary superior, style 1, stigmas 3.


Fruit drupe-like, globose, glabrous, about 5 mm. long.

Accepted Name:
Toxicodendron diversilobum (Torr. & A. Gray) Greene
Publication: Leafl. Bot. Observ. Crit. 1(9): 119. 1905.

Synonyms & Misapplications:
Rhus diversiloba Torr. & A. Gray [HC]
Toxicodendron radicans (L.) Kuntze ssp. diversilobum (Torr. & A. Gray) Thorne
Additional Resources:

PNW Herbaria: Specimen records of Toxicodendron diversilobum in the Consortium of Pacific Northwest Herbaria database

WA Flora Checklist: Toxicodendron diversilobum checklist entry

OregonFlora: Toxicodendron diversilobum information

E-Flora BC: Toxicodendron diversilobum atlas page

CalPhotos: Toxicodendron diversilobum photos

37 photographs:
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