Distribution: Occurring west of the Cascades crest in Washington, where currently considered endemic.
Habitat: Stream banks and moist, low woods at lower elevations.
Flowers: May-July
Origin: Native
Growth Duration: Perennial
Conservation Status: Not of concern
Pollination: Bumblebees, bees
Herbaceous perennial, with the stems arising singly from a branched, stout rhizome.
Leaves thin, scabrous above, prominently veined, the basal ones, if present, long-petiolate and cordate; cauline leaves numerous, short-petiolate, the blade broadly lanceolate to broadly ovate, pointed, 3-14 cm. long and 1.5-7 cm. wide, rounded at the base, gradually reduced upward.
Inflorescence branched and open; calyx 2-6 mm. long, cleft over half way to the base; corolla blue, 5-lobed, 9-16 mm. long, the limb 1.2 to 1.6 times as long as the tube; tube often with a ring of hairs below the middle within; filaments broad, shorter than the anthers; style longer than the corolla lobes; nutlets attached to the lower half of the style; hairy appendages opposite the corolla lobes at the top of the tube.
4 nutlets.
PNW Herbaria: Specimen records of Mertensia platyphylla in the Consortium of Pacific Northwest Herbaria database
WA Flora Checklist: Mertensia platyphylla checklist entry
OregonFlora: Mertensia platyphylla information
E-Flora BC: Mertensia platyphylla atlas page
CalPhotos: Mertensia platyphylla photos