C – C
| Calendula officinalis | Marigold |
| Calluna vulgaris | Heather |
| Capsella bursa pastoris | Shepherd’s purse |
| Capsicum annuuni | Capsicum |
| Carlina acaulis | Silver thistle |
| Carthamus tinctorius | Safflower |
| Carum carvi | Caraway |
| Castanea sativa | Sweet Chestnut |
| Catharanthus roseus | Madagascar periwinkle |
| Centaurea cyanus | Cornflower |
| Centaurium minus | European centaury |
| Centaurium umbellatum | Centaury |
| Chelidonium majus | Greater Calendula |
| Chenopodium ambrosioides | Wormseed |
| Chrysanthemum cineraria folium | Pyrethrum Daisy |
| Chrysanthemum Vulgare | Tansy seeds |
| Cichorium intybus | Chicory |
| Claviceps purpurea | Ergot of rye |
| Cnious Benedictus | Holy Thistle |
| Colchicum autumnale | Autumn Crocus |
| Conium maculatum | Poison Hemlock |
| Consolida Orientalis | Oriental knight’s-spur |
| Consolida regalis | Forking larkspur |
| Convallaria majalis | Lily of the valley |
| Convolvulus arvensis | Field bindweed |
| Coriandrum sativum | Coriander |
| Corylus avellana | Common hazel |
| Cotinus coggygria | European smoke tree |
| Crataegus monogyna | Hawthorn |
| Crataegus oxyacantha | Northern European hawthorn |
| Cuminum cyminum | Cumin |
| Cynara cardunculus | Cardoon, artichoke thistle |
| Cynara scolymus | Artichoke |
| Cynoglossum Officinalis | Houndstongue |
| Cytisus scoparius | Common broom, English broom, Scotch broom |