Page author: David Giblin
Petrophytum hendersonii
Olympic Mountain rockmat

Distribution: Occurring west of the Cascades crest, where endemic to the Olympic Mountains.

Habitat: Rocky cliffs and talus slopes at middle to high elevations.

Flowers: July-September

Origin: Native

Conservation Status: Not of concern


Densely-tufted, prostrate sub-shrub, the flowering stalks 1-5 cm. tall, with several bract-like leaves.


Leaves oblanceolate to spatulate-obovate, 10-20 mm. long and 2-6 mm. wide, 3-nerved, with silky hairs.


Inflorescence a tight raceme, 2-4 cm. long; calyx hemispheric, the 5 lobes oblong, reflexed, 2 mm. long; petals 5, white, oblong to oblong-obovate, 2-2.5 mm. long; stamens 35-40, pistils 5, the styles short, stout, hairy.


Fruit a follicle, barely 2 mm. long.

Accepted Name:
Petrophytum hendersonii (Canby) Rydb.
Publication: North American Flora 22(3): 253. 1908.

Synonyms & Misapplications:
Eriogynia hendersonii Canby
Luetkea hendersonii (Canby) Greene
Petrophyton hendersonii (Canby) Rydb., orthographic variant
Spiraea hendersonii (Canby) Piper
Additional Resources:

PNW Herbaria: Specimen records of Petrophytum hendersonii in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Petrophytum hendersonii checklist entry.

E-Flora BC: Petrophytum hendersonii atlas page.

CalPhotos: Petrophytum hendersonii photos.

USDA Plants: Petrophytum hendersonii information.

27 photographs:
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