Page authors: David Giblin, Don Knoke
Peritoma serrulata
guaco Rocky Mountain bee-plant, Rocky Mountain beeplant, guaco, stinkweed

Distribution: Occurring east of the Cascades crest in Washington; British Columbia to California, east to Ontario, the Great Lakes region, and Ohio.

Habitat: Sagebrush deserts and Ponderosa pine forest openings.

Flowers: June-August

Origin: Native

Growth Duration: Annual

Conservation Status: Not of concern


Freely-branched annual 2.5-10 dm. tall, usually glabrous or with a few long, soft hairs.


Leaves alternate, trifoliate, the leaflets linear-elliptic to narrowly lanceolate, 1.5-7 cm. long, exceeding the petioles,


Inflorescence of bracteate racemes, greatly elongate in fruit, the lowest of the flowers axillary to scarcely reduced leaves; pedicles 7-15 mm. long, calyx 2.5-3 mm. long, the 4 short, acute lobes not much longer than the tube; petals 4, reddish-purple to pale pink or white, ovate-lanceolate, 8-11 mm. long, narrowed abruptly to a claw 1 mm. long; stamens 6, the filaments twice the length of the petals, pink.


Capsule nearly terete, spreading or drooping, 3-6 cm. long, with a stipe 10-20 mm. long.

Accepted Name:
Peritoma serrulata (Pursh) DC.
Publication: Prodr. 1: 237. (as serrulatum). 1824.

Synonyms & Misapplications:
Cleome serrulata Pursh [HC]
Additional Resources:

PNW Herbaria: Specimen records of Peritoma serrulata in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Peritoma serrulata checklist entry.

OregonFlora: Peritoma serrulata information.

E-Flora BC: Peritoma serrulata atlas page.

CalPhotos: Peritoma serrulata photos.

USDA Plants: Peritoma serrulata information.

5 photographs:
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