Canada Thistle, Creeping Thistle: Cirsium arvense (Synonyms: Cirsium arvense var. arvense, Cirsium arvense var. horridum, Cirsium arvense var. mite) -
Short-styled Thistle, Clustered Thistle: Cirsium brevistylum -
Ashland Thistle: Cirsium ciliolatum -
Gray-green Thistle: Cirsium cymosum var. canovirens (Synonym: Cirsium canovirens) -
Edible Thistle, Indian Thistle: Cirsium edule var. edule (Synonym: Cirsium hallii)-
Cayuse Thistle, Edible Thistel: Cirsium edule var. macounii -
Wenatchee Thistle: Cirsium edule var. wenatchense -
Snowy Thistle, Snowwool Thistle: Cirsium occidentale var. candidissimum (Synonym: Cirsium pastoris) -
Mountain Thistle, Fringe-bract Thistle: Cirsium remotifolium var. odontolepis (Synonyms: Cirsium callilepis, Cirsium callilepis var. callilepis, Cirsium callilepis var. oregonense, Cirsium centaureae, Cirsium remotifolium ssp. oregonense, Cirsium remotifolium ssp. pseudocarlinoides) -
Few-leaf Thistle, Few-leaved Thistle, Pacific Fringed Thistle, Remote-leaved Thistle, Weak Thistle: Cirsium remotifolium var. remotifolium (Synonym: Cirsium remotifolium ssp. remotifolium) -
Dinnerplate Thistle, Elk Thistle, Meadow Thistle, Sessile Thistle, Shasta Valley Thistle, Stemless Thistle, Toiyabe Thistle: Cirsium scariosum (Synonyms: Carduus americanus, Carduus coloradensis, Cirsium acaule var. americanum, Cirsium acaulescens, Cirsium americanum, Cirsium butleri, Cirsium coloradense, Cirsium coloradense ssp. acaulescens, Cirsium coloradense ssp. longissimum, Cirsium congdonii, Cirsium drummondii ssp. lanatum, Cirsium drummondii ssp. lanatum, Cirsium drummondii ssp. latisquamum, Cirsium drummondii ssp. vexans, Cirsium drummondii var. acaulescens, Cirsium drummondii var. oregonense, Cirsium erosum, Cirsium hookerianum var. scariosum, Cirsium kelsey, Cirsium lacerum, Cirsium magnificum, Cirsium minganense, Cirsium oreophilum, Cirsium quercetorum, Cirsium scariosum var. americanum, Cirsium scariosum var. robustum, Cirsium scariosum var. scariosum, Cirsium scariosum var. thorneae, Cirsium scariosum var. toiyabense, Cirsium tioganum, Cirsium tioganum var. coloradense, Cirsium tioganum var. tioganum, Cnicus drummondii var. acaulescens, Cnicus tioganus) -
Wavyleaf Thistle: Cirsium undulatum (Synonym: Cirsium undulatum var. undulatum) -
Bull Thistle, Common Thistle: Cirsium vulgare (Synonym: Carduus vulgare) -