Carduus
plumeless thistle
4 species
2 subspecies and varieties
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Carduus acanthoidesplumeless thistle, spiny plumeless thistle
Distribution: Introduced in much of the United States; uncommon in Washington and Idaho
Habitat: Disturbed, dry ground.
Origin: Introduced from Europe
Flowers: July - October
Carduus nutansmusk thistle, nodding thistle
Distribution: Scattered introductions throughout the Pacific Northwest
Habitat: Moderately dry, open areas
Origin: Introduced
Flowers: June - October
Carduus pycnocephalusItalian plumeless thistle
Distribution: Known from Clallam County in Washington; 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
ssp. pycnocephalus – Italian plumeless thistle
Carduus tenuiflorusslender flowered thistle, winged plumeless thistle
Distribution: Introduced in western WA; south to California and sparingly introduced in eastern U.S.
Habitat: Disturbed areas at low elevation
Origin: Introduced
Flowers: June-July