| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| CIPA | Cirsium parryi (Gray) Petrak | Parry's thistle | Asteraceae
|
| CIPA2 | Cirsium pastoris J.T. Howell | snowy thistle | Asteraceae
|
| CIPE4 | Cirsium peckii Henderson | Steen Mountain thistle | Asteraceae
|
| CIPE | Cirsium perennans (Greene) Woot. & Standl. | Cirsium wheeleri | Asteraceae
|
| CIPE5 | Cirsium perplexans (Rydb.) Petrak | Rocky Mountain thistle | Asteraceae
|
| CIPI | Cirsium pitcheri (Torr. ex Eat.) Torr. & Gray | sand dune thistle | Asteraceae
|
| CIPL2 | Cirsium plattense (Rydb.) Cockerell ex Daniels | Cirsium canescens | Asteraceae
|
| CIPO | Cirsium polyphyllum (Rydb.) Petrak | Cirsium eatonii | Asteraceae
|
| CIPR2 | Cirsium praeteriens J.F. Macbr. | Palo Alto thistle | Asteraceae
|
| CIPR | Cirsium proteanum J.T. Howell | Cirsium occidentale var. venustum | Asteraceae
|
| CIPU6 | Cirsium pugnax Sommier & Levier | Cnicus benedictus | Asteraceae
|
| CIPUB | Cirsium pulchellum (Greene) Woot. & Standl. ssp. bipinnatum (Eastw.) Petrak | Cirsium calcareum | Asteraceae
|
| CIPUD | Cirsium pulchellum (Greene) Woot. & Standl. ssp. diffusum (Eastw.) Petrak | Cirsium rothrockii | Asteraceae
|
| CIPUG | Cirsium pulchellum (Greene) Woot. & Standl. var. glabrescens Petrak | Cirsium calcareum | Asteraceae
|
| CIPU2 | Cirsium pulchellum (Greene) Woot. & Standl. | Cirsium calcareum | Asteraceae
|
| CIPU3 | Cirsium pulcherrimum (Rydb.) K. Schum. | Wyoming thistle | Asteraceae
|
| CIPUH | Cirsium pumilum (Nutt.) Spreng. ssp. hillii (Canby) Moore & Frankton | Cirsium hillii | Asteraceae
|
| CIPUH2 | Cirsium pumilum (Nutt.) Spreng. var. hillii (Canby) Boivin | Cirsium hillii | Asteraceae
|
| CIPU4 | Cirsium pumilum (Nutt.) Spreng. | pasture thistle | Asteraceae
|
| CIPY2 | Cirsium pyrenaicum (Jacq.) All. | | Asteraceae
|
| CIQUC4 | Cirsium quercetorum (Gray) Jepson var. citrinum Petrak | Cirsium tioganum var. tioganum | Asteraceae
|
| CIQUM | Cirsium quercetorum (Gray) Jepson var. mendocinum Petrak | Cirsium quercetorum var. quercetorum | Asteraceae
|
| CIQUQ | Cirsium quercetorum (Gray) Jepson var. quercetorum | Alameda County thistle | Asteraceae
|
| CIQUW | Cirsium quercetorum (Gray) Jepson var. walkerianum (Petrak) Jepson | Walker's thistle | Asteraceae
|
| CIQUX | Cirsium quercetorum (Gray) Jepson var. xerolepis Petrak | Alameda County thistle | Asteraceae
|
| CIQU2 | Cirsium quercetorum (Gray) Jepson | Alameda County thistle | Asteraceae
|
| CIREO2 | Cirsium remotifolium (Hook.) DC. ssp. oregonense Petrak | fewleaf thistle | Asteraceae
|
| CIREP | Cirsium remotifolium (Hook.) DC. ssp. pseudocarlinoides Petrak | fewleaf thistle | Asteraceae
|
| CIRER3 | Cirsium remotifolium (Hook.) DC. ssp. remotifolium | fewleaf thistle | Asteraceae
|
| CIREO | Cirsium remotifolium (Hook.) DC. var. odontolepis Petrak | Cirsium remotifolium ssp. remotifolium | Asteraceae
|
| CIRER2 | Cirsium remotifolium (Hook.) DC. var. rivulare Jepson | Cirsium remotifolium ssp. remotifolium | Asteraceae
|
| CIRE | Cirsium remotifolium (Hook.) DC. | fewleaf thistle | Asteraceae
|
| CIRE2 | Cirsium repandum Michx. | sandhill thistle | Asteraceae
|
| CIRE4 | Cirsium revolutum (Small) Petrak | Cirsium virginianum | Asteraceae
|
| CIRH | Cirsium rhothophilum Blake | surf thistle | Asteraceae
|
| CIRO | Cirsium rothrockii (Gray) Petrak | Rothrock's thistle | Asteraceae
|
| CIRU2 | Cirsium rusbyi (Greene) Petrak | Rusby's thistle | Asteraceae
|
| CIRY | Cirsium rydbergii Petrak | Rydberg's thistle | Asteraceae
|
| CISC4 | Cirsium scabrum (Poir.) Bonnet & Barratte | rough thistle | Asteraceae
|
| CISC | Cirsium scapanolepis Petrak | mountain slope thistle | Asteraceae
|
| CISCS | Cirsium scariosum Nutt. var. scariosum | meadow thistle | Asteraceae
|
| CISCT | Cirsium scariosum Nutt. var. thorneae Welsh | meadow thistle | Asteraceae
|
| CISC2 | Cirsium scariosum Nutt. | meadow thistle | Asteraceae
|
| CISC3 | Cirsium scopulorum (Greene) Cockerell ex Daniels | mountain thistle | Asteraceae
|
| CISE | Cirsium setosum (Willd.) Bess. ex Bieb. | Cirsium arvense | Asteraceae
|
| CISM | Cirsium smallii Britt. | Cirsium horridulum var. horridulum | Asteraceae
|
| CISP5 | Cirsium spathulifolium Rydb. | Cirsium scapanolepis | Asteraceae
|
| CISP4 | Cirsium spinosissimum auct. non (L.) Scop. | Cirsium horridulum var. horridulum | Asteraceae
|
| CIST2 | Cirsium stenolepidum Nutt. | Cirsium remotifolium ssp. remotifolium | Asteraceae
|
| CISU | Cirsium subniveum Rydb. | Jackson Hole thistle | Asteraceae
|
| CITE | Cirsium terraenigrae Shinners | Cirsium engelmannii | Asteraceae
|
| CITES | Cirsium texanum Buckl. var. stenolepis Shinners | Cirsium texanum | Asteraceae
|
| CITE2 | Cirsium texanum Buckl. | Texas thistle | Asteraceae
|
| CITIC | Cirsium tioganum (Congd.) Petrak var. coloradense (Rydb.) Dorn | Colorado thistle | Asteraceae
|
| CITIT | Cirsium tioganum (Congd.) Petrak var. tioganum | Tioga thistle | Asteraceae
|
| CITI | Cirsium tioganum (Congd.) Petrak | stemless thistle | Asteraceae
|
| CITR4 | Cirsium tracyi (Rydb.) Petrak | Cirsium undulatum var. tracyi | Asteraceae
|
| CITR6 | Cirsium triacanthum Petrak | Cirsium cymosum | Asteraceae
|
| CITU | Cirsium turneri Warnock | cliff thistle | Asteraceae
|
| CITW | Cirsium tweedyi (Rydb.) Petrak | Cirsium eatonii | Asteraceae
|
| CITW3 | Cirsium tweedyi auct. non (Rydb.) Petrak | Cirsium murdockii | Asteraceae
|
| CIUNM | Cirsium undulatum (Nutt.) Spreng. var. megacephalum (Gray) Fern. | Cirsium undulatum var. undulatum | Asteraceae
|
| CIUNT | Cirsium undulatum (Nutt.) Spreng. var. tracyi (Rydb.) Welsh | Tracy's thistle | Asteraceae
|
| CIUNU | Cirsium undulatum (Nutt.) Spreng. var. undulatum | wavyleaf thistle | Asteraceae
|
| CIUN | Cirsium undulatum (Nutt.) Spreng. | wavyleaf thistle | Asteraceae
|
| CIUT | Cirsium utahense Petrak | Cirsium neomexicanum var. utahense | Asteraceae
|
| CIVAH | Cirsium vaseyi (Gray) Jepson var. hydrophilum (Greene) Petrak | Cirsium hydrophilum var. hydrophilum | Asteraceae
|
| CIVA4 | Cirsium vaseyi (Gray) Jepson | Cirsium hydrophilum var. vaseyi | Asteraceae
|
| CIVE | Cirsium vernale (Osterhout) Cockerell | spring thistle | Asteraceae
|
| CIVI4 | Cirsium vinaceum Woot. & Standl. | Sacramento Mountain thistle | Asteraceae
|
| CIVI6 | Cirsium virginense Welsh | virgin thistle | Asteraceae
|
| CIVI | Cirsium virginianum (L.) Michx. | Virginia thistle | Asteraceae
|
| CIVI7 | Cirsium vittatum Small | Cirsium horridulum var. vittatum | Asteraceae
|
| CIVU | Cirsium vulgare (Savi) Ten. | bull thistle | Asteraceae
|
| CIWA3 | Cirsium walkerianum Petrak | Cirsium quercetorum var. walkerianum | Asteraceae
|
| CIWA2 | Cirsium wallowense M.E. Peck | Cirsium neomexicanum var. utahense | Asteraceae
|
| CIWH | Cirsium wheeleri (Gray) Petrak | Wheeler's thistle | Asteraceae
|
| CIWR | Cirsium wrightii Gray | Wright's thistle | Asteraceae
|
| CIRSI | Cirsium P. Mill. | thistle | Asteraceae
|
| CIPA4 | Cissampelos pareira L. | pareira brava | Menispermaceae
|
| CISSA | Cissampelos L. | cissampelos | Menispermaceae
|
| CIAM6 | Cissus ampelopsis Pers. | Ampelopsis cordata | Vitaceae
|
| CIAN3 | Cissus antarctica Vent. | kangaroo vine | Vitaceae
|
| CICA9 | Cissus caustica Tussac | Cissus obovata | Vitaceae
|
| CIER | Cissus erosa L.C. Rich. | caro de tres hojas | Vitaceae
|
| CIIN2 | Cissus incisa auct. non Des Moulins | Cissus trifoliata | Vitaceae
|
| CIIN3 | Cissus intermedia A. Rich. | intermediate treebine | Vitaceae
|
| CINO | Cissus nodosa Blume | Javanese treebine | Vitaceae
|
| CIOB | Cissus obovata Vahl | spoonleaf treebine | Vitaceae
|
| CIRE5 | Cissus repens Lam. | cissus | Vitaceae
|
| CIRH2 | Cissus rhombifolia Vahl | grape ivy | Vitaceae
|
| CIRO3 | Cissus rotundifolia (Forssk.) Vahl | Venezuelan treebine | Vitaceae
|
| CISI2 | Cissus sicyoides L. | Cissus verticillata | Vitaceae
|
| CITR2 | Cissus trifoliata (L.) L. | sorrelvine | Vitaceae
|
| CITU2 | Cissus tuberculata Jacq. | West Indian treebine | Vitaceae
|
| CIVE3 | Cissus verticillata (L.) D.H. Nicols. & Jarvis | seasonvine | Vitaceae
|
| CISSU | Cissus L. | treebine | Vitaceae
|
| CIAM3 | Cistanthe ambigua (S. Wats.) Hershkovitz | desert pussypaws | Portulacaceae
|
| CIMA4 | Cistanthe maritima (Nutt.) Hershkovitz | seaside pussypaws | Portulacaceae
|
| CIMO4 | Cistanthe monandra (Nutt.) Hershkovitz | common pussypaws | Portulacaceae
|
| CIMO5 | Cistanthe monosperma (Greene) Hershkovitz | oneseed pussypaws | Portulacaceae
|