Anderson's Thistle: Cirsium andersonii - Uncommon. Only found west of the Cascade Mountains near Coos Bay.
Canada Thistle, Creeping Thistle: Cirsium arvense (Synonyms: Cirsium arvense var. arvense, Cirsium arvense var. horridum) -
Clustered Thistle, Short-styled Thistle: Cirsium brevistylum -
Ashland Thistle: Cirsium ciliolatum -
Brewer's Thistle: Cirsium douglasii var. breweri (Synonyms: Cirsium breweri, Cirsium douglasii var. canescens) -
Edible Thistle, Indian Thistle: Cirsium edule var. edule (Synonym: Cirsium hallii) -
Edible Thistle, Indian Thistle, Macoun's Thistle: Cirsium edule var. macounii (Synonyms: Carduus macounii, Cirsium macounii) -
Snowwool Thistle, Snowy Thistle: Cirsium occidentale var. candidissimum (Synonym: Cirsium pastoris) -
Venus Thistle: Cirsium occidentale var. venustum (Syonynm: Cirsium proteanum) -
Fringe-bract Thistle, Mountain Thistle, Pacific Fringed Thistle, Remote-leaved Thistle: Cirsium remotifolium var. odontolepis (Synonyms: Carduus remotifolius, Cirsium callilepis, Cirsium callilepis var. callilepis, Cirisum callilepis var. oregonense, Cirsium callilepsis var. pseudocarlinoides, Cirsium centaureae, Cirsium remotifolium ssp. oregonense, Cirsium remotifolium ssp. pseudocarlinoides) -
Few-leaved Thistle, Weak Thistle: Cirsium remotifolium var. remotifolium (Synonym: Cirsium remotifolium ssp. remotifolium) -
Klamath Thistle: Cirsium remotifolium var. rivulare (Synonym: Cirsium acanthodontum) -
Dinnerplate Thistle, Elk Thistle, Meadow Thistle: Cirsium scariosum (Synonyms: Cirsium americanum, Cirsium foliosum, Cirsium hookerianum var. scariosum, Cirsium magnificum, Cirsium scariosum var. americanum, Cirsium scariosum var. citrinum, Cirsium scariosum var. coloradense, Cirsium scariosum var. congdonii, Cirsium scariosum var. robustum, Cirsium scariosum var. scariosum, Cirsium scariosum var. thorneae, Cirsium scariosum var. toiyabense, Cirsium tioganum, Cirsium tioganum var. tioganum) -
Wavyleaf Thistle, Wavy-leaf Thistle: Cirsium undulatum (Synonym: Cirsium undulatum var. undulatum) -
Bull Thistle, Common Thistle: Cirsium vulgare (Synonym: Carduus vulgare) -