Carduus
plumeless thistle
4 species
2 subspecies and varieties
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Carduus acanthoidesplumeless thistle, spiny plumeless thistle
Distribution: Occurring east of the Cascades crest in northeastern Washington; British Columbia to Washington, also in California, east to the northern Rocky Mountains, Great Plains, and eastern North America.
Habitat: Roadsides, fields, ditches, and other disturbed, open areas.
Origin: Introduced from Europe
Flowers: July-October
Growth Duration: Biennial
Carduus nutansmusk thistle, nodding thistle
Distribution: Occurring in scattered locations on both sides of the Cascades crest in Washington; British Columbia to California, east to the Atlantic Coast.
Habitat: Roadsides, fields, ditches, wastelots, and other disturbed, open areas.
Origin: Introduced from Eurasia
Flowers: June-October
Growth Duration: Biennial, Perennial
Carduus pycnocephalusshore thistle
Distribution: Occurring west of the Cascades crest in Washington, where known only from Clallam County; Washington to California and Idaho, also in central and eastern U.S.
Habitat: Disturbed, open areas at low elevation.
Origin: Introduced from Europe
Flowers: June-July
Growth Duration: Annual
ssp. pycnocephalus – Italian plumeless thistle
Carduus tenuiflorusslender flowered thistle, winged plumeless thistle
Distribution: Occurring west of the Cascades crest in southwestern Washington; Washington to California, also in the eastern U.S.
Habitat: Roadsides, fields, ditches, wastelots, and other disturbed areas at low elevations.
Origin: Introduced from Europe
Flowers: June-July
Growth Duration: Annual