Cyrto-hypnum pygmaeum - Desmanthus obtusus
- Cyrto-hypnum pygmaeum
- Cyrto-hypnum schistocalyx
- Cyrtococcum
- Cyrtococcum oxyphyllum
- Cyrtococcum patens
- Cyrtomium
- Cyrtomium caryotideum
- Cyrtomium falcatum
- Cyrtomium fortunei
- Cyrtomnium
- Cyrtomnium hymenophylloides
- Cyrtomnium hymenophyllum
- Cyrtopodium
- Cyrtopodium andersonii
- Cyrtopodium polyphyllum
- Cyrtopodium punctatum
- Cyrtosperma
- Cyrtosperma chamissonis
- Cyrtosperma merkusii
- Cystobasidium
- Cystobasidium hypogymniicola
- Cystobasidium usneicola
- Cystocoleus
- Cystocoleus ebeneus
- Cystopteris
- Cystopteris bulbifera
- Cystopteris douglasii
- Cystopteris fragilis
- Cystopteris illinoensis
- Cystopteris laurentiana
- Cystopteris montana
- Cystopteris protrusa
- Cystopteris reevesiana
- Cystopteris tennesseensis
- Cystopteris tenuis
- Cystopteris utahensis
- Cystopteris wagneri
- Cytisophyllum
- Cytisophyllum sessilifolius
- Cytisus
