Distribution: Occurring chiefly east of the Cascades crest in Washington; Alaska to California, east across North America to the Atlantic Coast.
Habitat: Shrub-steppe, grasslands, and waste ground, especially following rangeland fires.
Flowers: May-September
Origin: Introduced from Eurasia
Growth Duration: Annual, Biennial
Conservation Status: Not of concern
Pollination: Bees, flies, butterflies
Annual herb, the erect, freely-branching stems 3-15 dm. tall, glabrous above and with a few stiff hairs below.
Leaves alternate, broadly lanceolate or oblong to oblanceolate, up to 1.5 dm. long, petiolate, the lower ones pinnatifid, the segments often pointing backward, becoming pinnatifid with linear segments above.
Inflorescence of bractless racemes; pedicles stout, spreading, 4-10 mm. long; sepals 4, somewhat spreading, 4 mm. long; petals 4, pale yellowish, clawed, 6-8 mm. long; stamens 6; style lacking, stigma 2-lobed.
Siliques linear, terete, 5-10 cm. long, slightly broader than the pedicles, spreading and rigid; valves with a prominent mid-nerve and 2 evident lateral nerves; seeds in 1 series.
PNW Herbaria: Specimen records of Sisymbrium altissimum in the Consortium of Pacific Northwest Herbaria database
WA Flora Checklist: Sisymbrium altissimum checklist entry
OregonFlora: Sisymbrium altissimum information
E-Flora BC: Sisymbrium altissimum atlas page
CalPhotos: Sisymbrium altissimum photos