| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| CIDOC | Cirsium douglasii DC. var. canescens (Petrak) J.T. Howell | Cirsium douglasii var. breweri | Asteraceae
|
| CIDOD | Cirsium douglasii DC. var. douglasii | Douglas' thistle | Asteraceae
|
| CIDO2 | Cirsium douglasii DC. | Douglas' thistle | Asteraceae
|
| CIDRL | Cirsium drummondii Torr. & Gray ssp. lanatum Petrak | Cirsium tioganum var. tioganum | Asteraceae
|
| CIDRL2 | Cirsium drummondii Torr. & Gray ssp. latisquamum Petrak | Cirsium tioganum var. tioganum | Asteraceae
|
| CIDRV | Cirsium drummondii Torr. & Gray ssp. vexans Petrak | Cirsium tioganum var. tioganum | Asteraceae
|
| CIDRA | Cirsium drummondii Torr. & Gray var. acaulescens (Rydb.) J.F. Macbr. | Cirsium tioganum var. tioganum | Asteraceae
|
| CIDRO | Cirsium drummondii Torr. & Gray var. oregonense Petrak | Cirsium tioganum var. tioganum | Asteraceae
|
| CIDR2 | Cirsium drummondii Torr. & Gray | dwarf thistle | Asteraceae
|
| CIEAH | Cirsium eatonii (Gray) B.L. Robins. var. harrisonii Welsh | Cirsium eatonii | Asteraceae
|
| CIEAM | Cirsium eatonii (Gray) B.L. Robins. var. murdockii Welsh | Cirsium murdockii | Asteraceae
|
| CIEA | Cirsium eatonii (Gray) B.L. Robins. | Eaton's thistle | Asteraceae
|
| CIED | Cirsium edule Nutt. | edible thistle | Asteraceae
|
| CIEN2 | Cirsium engelmannii Rydb. | Engelmann's thistle | Asteraceae
|
| CIERL | Cirsium eriocephalum Gray var. leiocephalum D.C. Eat. | Cirsium eatonii | Asteraceae
|
| CIER3 | Cirsium eriocephalum Gray | Cirsium scopulorum | Asteraceae
|
| CIER2 | Cirsium �erosum (Rydb.) K. Schum. (pro sp.) | glory thistle | Asteraceae
|
| CIFI | Cirsium filipendulum Engelm. | Cirsium engelmannii | Asteraceae
|
| CIFL2 | Cirsium flaccidum Small | Cirsium carolinianum | Asteraceae
|
| CIFL3 | Cirsium floccosum (Rydb.) Petrak | Cirsium undulatum var. tracyi | Asteraceae
|
| CIFL | Cirsium flodmanii (Rydb.) Arthur | Flodman's thistle | Asteraceae
|
| CIFOM | Cirsium foliosum (Hook.) DC. var. minganense (Victorin) Boivin | Cirsium foliosum | Asteraceae
|
| CIFO | Cirsium foliosum (Hook.) DC. | elk thistle | Asteraceae
|
| CIFOC | Cirsium fontinale (Greene) Jepson var. campylon (H.K. Sharsmith) Pilz ex Keil & C. Turner | Mt Hamilton thistle | Asteraceae
|
| CIFOF | Cirsium fontinale (Greene) Jepson var. fontinale | fountain thistle | Asteraceae
|
| CIFOO | Cirsium fontinale (Greene) Jepson var. obispoense J.T. Howell | Chorro Creek Bog thistle | Asteraceae
|
| CIFO2 | Cirsium fontinale (Greene) Jepson | fountain thistle | Asteraceae
|
| CIGI | Cirsium gilense Woot. & Standl. | Gila thistle | Asteraceae
|
| CIGR2 | Cirsium grahamii Gray | Graham's thistle | Asteraceae
|
| CIGR3 | Cirsium griseum (Rydb.) K. Schum. | gray thistle | Asteraceae
|
| CIHA | Cirsium hallii (Gray) M.E. Jones | Hall's thistle | Asteraceae
|
| CIHE5 | Cirsium helleri (Small) Cory | Cirsium undulatum var. undulatum | Asteraceae
|
| CIHE4 | Cirsium hesperium (Eastw.) Petrak | Cirsium scopulorum | Asteraceae
|
| CIHI | Cirsium hillii (Canby) Fern. | Hill's thistle | Asteraceae
|
| CIHOE2 | Cirsium hookerianum Nutt. var. eriocephalum (Gray) A. Nels. | Cirsium eatonii | Asteraceae
|
| CIHO | Cirsium hookerianum Nutt. | white thistle | Asteraceae
|
| CIHOE | Cirsium horridulum Michx. var. elliottii Torr. & Gray | Cirsium horridulum var. horridulum | Asteraceae
|
| CIHOH | Cirsium horridulum Michx. var. horridulum | yellow thistle | Asteraceae
|
| CIHOV | Cirsium horridulum Michx. var. vittatum (Small) R.W. Long | yellow thistle | Asteraceae
|
| CIHO2 | Cirsium horridulum Michx. | yellow thistle | Asteraceae
|
| CIHO4 | Cirsium howellii Petrak | Cirsium ciliolatum | Asteraceae
|
| CIHU | Cirsium humboldtense Rydb. | Humboldt County thistle | Asteraceae
|
| CIHYH | Cirsium hydrophilum (Greene) Jepson var. hydrophilum | Suisun thistle | Asteraceae
|
| CIHYV | Cirsium hydrophilum (Greene) Jepson var. vaseyi (Gray) J.T. Howell | Vasey's thistle | Asteraceae
|
| CIHY | Cirsium hydrophilum (Greene) Jepson | Suisun thistle | Asteraceae
|
| CIIN7 | Cirsium incanum (Gmel.) Fisch. | Cirsium arvense | Asteraceae
|
| CIIN5 | Cirsium inornatum Woot. & Standl. | cloudcroft thistle | Asteraceae
|
| CIIO2 | Cirsium �iowense (Pammel) Fern. (pro sp.) | | Asteraceae
|
| CIJA2 | Cirsium japonicum Fisch. ex DC. | Japanese thistle | Asteraceae
|
| CIKA | Cirsium kamtschaticum Ledeb. ex DC. | Kamchatka thistle | Asteraceae
|
| CIKE | Cirsium kelseyi (Rydb.) Petrak | Cirsium scariosum var. scariosum | Asteraceae
|
| CILA4 | Cirsium lacerum (Rydb.) Petrak | Cirsium scariosum var. scariosum | Asteraceae
|
| CILA7 | Cirsium lactucinum Rydb. | Cirsium rydbergii | Asteraceae
|
| CILAH | Cirsium lanceolatum (L.) Scop. var. hypoleucum DC. | Cirsium vulgare | Asteraceae
|
| CILA8 | Cirsium lanceolatum (L.) Scop., non Hill | Cirsium vulgare | Asteraceae
|
| CILA5 | Cirsium laterifolium (Osterhout) Petrak | porcupine thistle | Asteraceae
|
| CILE2 | Cirsium lecontei Torr. & Gray | Le Conte's thistle | Asteraceae
|
| CILO | Cirsium loncholepis Petrak | la graciosa thistle | Asteraceae
|
| CILO2 | Cirsium longistylum Moore & Frankton | longstyle thistle | Asteraceae
|
| CIMA7 | Cirsium macounii (Greene) Rydb. | Cirsium edule | Asteraceae
|
| CIMA3 | Cirsium magnificum (A. Nels.) Petrak | Cirsium scariosum var. scariosum | Asteraceae
|
| CIMA8 | Cirsium maritimum (Elmer) Petrak | Cirsium rhothophilum | Asteraceae
|
| CIME7 | Cirsium megacephalum (Gray) Cockerell | Cirsium undulatum var. undulatum | Asteraceae
|
| CIME5 | Cirsium mendocinum Petrak | Mendocino thistle | Asteraceae
|
| CIME4 | Cirsium mexicanum DC. | Mexican thistle | Asteraceae
|
| CIMI | Cirsium minganense Victorin | Cirsium scariosum var. scariosum | Asteraceae
|
| CIMO2 | Cirsium modestum (Osterhout) Cockerell | lacy thistle | Asteraceae
|
| CIMO | Cirsium mohavense (Greene) Petrak | Mojave thistle | Asteraceae
|
| CIMO6 | Cirsium montigenum Petrak | Cirsium hydrophilum var. vaseyi | Asteraceae
|
| CIMU2 | Cirsium murdockii (Welsh) Cronq. | Murdock's thistle | Asteraceae
|
| CIMUM | Cirsium muticum Michx. var. monticola Fern. | Cirsium muticum | Asteraceae
|
| CIMUS | Cirsium muticum Michx. var. subpinnatifidum (Britt.) Fern. | Cirsium muticum | Asteraceae
|
| CIMU | Cirsium muticum Michx. | swamp thistle | Asteraceae
|
| CINA | Cirsium navajoense Moore & Frankton | Navajo thistle | Asteraceae
|
| CINED | Cirsium nebraskense (Britt.) Lunell var. discissum Lunell | Cirsium flodmanii | Asteraceae
|
| CINE3 | Cirsium nebraskense (Britt.) Lunell | Cirsium canescens | Asteraceae
|
| CINE4 | Cirsium nelsonii (Pammel) Petrak | Cirsium canescens | Asteraceae
|
| CINEN | Cirsium neomexicanum Gray var. neomexicanum | New Mexico thistle | Asteraceae
|
| CINEU | Cirsium neomexicanum Gray var. utahense (Petrak) Welsh | Utah thistle | Asteraceae
|
| CINE | Cirsium neomexicanum Gray | New Mexico thistle | Asteraceae
|
| CINI | Cirsium nidulum (M.E. Jones) Petrak | Cirsium arizonicum var. nidulum | Asteraceae
|
| CINU | Cirsium nuttallii DC. | Nuttall's thistle | Asteraceae
|
| CIOB2 | Cirsium oblanceolatum (Rydb.) K. Schum. | Cirsium flodmanii | Asteraceae
|
| CIOCC4 | Cirsium occidentale (Nutt.) Jepson var. californicum (Gray) Keil & C. Turner | cobwebby thistle | Asteraceae
|
| CIOCC | Cirsium occidentale (Nutt.) Jepson var. candidissimum (Greene) J.F. Macbr. | Cirsium pastoris | Asteraceae
|
| CIOCC2 | Cirsium occidentale (Nutt.) Jepson var. compactum Hoover | compact cobwebby thistle | Asteraceae
|
| CIOCO | Cirsium occidentale (Nutt.) Jepson var. occidentale | cobwebby thistle | Asteraceae
|
| CIOCV | Cirsium occidentale (Nutt.) Jepson var. venustum (Greene) Jepson | cobwebby thistle | Asteraceae
|
| CIOC | Cirsium occidentale (Nutt.) Jepson | cobwebby thistle | Asteraceae
|
| CIOCH | Cirsium ochrocentrum Gray var. helleri (Small) Petrak | Cirsium undulatum var. undulatum | Asteraceae
|
| CIOC2 | Cirsium ochrocentrum Gray | yellowspine thistle | Asteraceae
|
| CIOD | Cirsium odoratum (Muhl. ex W. Bart.) Petrak | Cirsium pumilum | Asteraceae
|
| CIOL | Cirsium olivescens (Rydb.) Petrak | summer thistle | Asteraceae
|
| CIOR2 | Cirsium oreganum Piper | Cirsium remotifolium ssp. remotifolium | Asteraceae
|
| CIOR | Cirsium oreophilum (Rydb.) K. Schum. | crow thistle | Asteraceae
|
| CIOS | Cirsium osterhoutii (Rydb.) Petrak | Osterhout's thistle | Asteraceae
|
| CIOW | Cirsium ownbeyi Welsh | Ownbey's thistle | Asteraceae
|
| CIPA5 | Cirsium pallidum Woot. & Standl. | pale thistle | Asteraceae
|
| CIPA9 | Cirsium palousense Piper | Cirsium brevifolium | Asteraceae
|
| CIPA6 | Cirsium palustre (L.) Scop. | marsh thistle | Asteraceae
|
| CIPAM | Cirsium parryi (Gray) Petrak ssp. mogollonicum C. Schaack & G. Goodwin | Mogollon thistle | Asteraceae
|