The following names have already been used within the genus and therefore cannot be re-used. This list is not in strict alphabetical order but is sorted including spaces, full stops etc. in row order. To look at other names click on the appropriate first letter.
| C. W. Nix | Caekerton White | Caerketton White | Cairnwell |
| CaJo | Caleb Threlkeld | Calf of Man | California Lilac |
| California Midge | Californian Midge | Californian Ridge | Camala |
| Camilla | Camilta | Camla | Camla Variety |
| Camlaensis | Candide | Cape Wrath | Carina |
| Carl Roder | Carl Röders | Carlton | Carmelita |
| Carmen | Carmina | Carmiro | Carn Gold |
| Carngold | Carol Island | Carole Chapman | Carolin |
| Carolyn | Carrington | Carrington, Sir John | Cassa |
| Castle of Mey | Catherine | Catherine Anne | Cearketton White |
| Celina | Celtic Gold | Cerda | Charles Chapman |
| Charmaine | Charmington | Charrington | Chase White |
| Cheese Ring | Cheesewring | Chernobyl | Cheyenne |
| Chindit | Christa | Christin | Christina |
| Christine | Christmas Candle | Christopher Dover | Cilcennin Common |
| Cinderella | Cindy | Citronella | Clare Carpet |
| Claudette | Cleistogamia | Cleopatra | Co. Wicklow |
| Coby | Coccinea | Coccinea Silver | Coccinea Smith's Variety |
| Colette | Colorado | Con Brio | Conachair |
| Concorde | Contorta | Contorted | Copper Glow |
| Copper Splendour | Coral Island | Corbett's Red | Corbett's White |
| Cornferry | Cornish White | Corran Ferry | Corrie's White |
| Corries's White | Cottswood Gold | Countess of Home | Country Wicklow |
| County Antrim | County Limerick | County of Wicklow | County Wicklow |
| Craig Rossie | Crail Orange | Cramond | Crasmeriensis |
| Cream Steving | Crimson Beauty | Crimson Glory | Crimson Glow |
| Crimson Gold | Crimson Sunset | Crimson Variegata | Crinkly Tuft |
| Crispa | Cronix | Crowborough Beacon | Cunneryensis |
| Cuperette | Cupraea | Cupraeus | Cuprea |
| Cuprea Flore Pleno | Cuprea Select | Curly Carpet | curtisepala |
| Cutler's Pink | Cyndy |
© The Heather Society, 4 January 2007