Distribution: Known sparingly in Washington from lowland areas west of Cascades crest; southwestern British Columbia to California, east across northern U.S. to eastern North America.
Habitat: Yard waste dump sites, disturbed open ground, and other sites were plants escape from cultivation.
Origin: Introduced from Eurasia
Growth Duration: Annual
Conservation Status: Not of concern
Delicate annual, the stem simple or branched, 10-50 cm. tall.
Leaves alternate, bi-or tri-pinnate, the segments liner-lanceolate, about 1 mm. broad.
Flowers solitary, surrounded by a ring of pinnate bracts; sepals several, bluish, spreading, clawed, oblong-ovate, 1.5-2 cm. long; petals none in double-flowered individual plants, but single-flowered plants often have petals; stamens many.
Carpels joined together their entire length, forming a spherical, inflated fruit.