Distribution: Occurring chiefly in the Columbia River Gorge in Washington, but disjunct in the northern Olympic Peninsula; disjunct in southwestern British Columbia and the northern Olympic Peninsula, otherwise southern Washington to central California.
Habitat: Fairly moist in open to partly shaded places at low elevations.
Flowers: March-May
Origin: Native
Growth Duration: Annual
Conservation Status: Not of concern
Glabrous annual, the stem slender and weak, often branched, 0.5-2.5 dm. tall.
Leaves opposite, small, the blade under 2 cm. long; lowermost leaves petiolate, with broad, toothed blade; next higher leaves trifoliate, with broad segments; middle and upper leaves with progressively shorter petioles and narrower segments, the uppermost reduced and entire.
Flowers several, 1 or more in the axils of reduced leaves, on elongate, slender, stipitate-glandular pedicels; calyx with 5 lobes longer than the tube; corolla blue, inconspicuous, 2-4 mm. wide, with a short tube with 5 lobes, slightly bilabiate; stamens 4.
Capsule opening along 4 sutures.
PNW Herbaria: Specimen records of Tonella tenella in the Consortium of Pacific Northwest Herbaria database
WA Flora Checklist: Tonella tenella checklist entry
OregonFlora: Tonella tenella information
E-Flora BC: Tonella tenella atlas page
CalPhotos: Tonella tenella photos