| Caesalpinia bonduc | Caesalpinia crista, Guilandina bonduc |
| Caesalpinia decapetala | Biancaea decapetala, Biancaea sepiaria, Caesalpinia sepiaria, Reichardia decapetala |
| Caesalpinia spinosa | Poinciana spinosa, Tara spinosa, Caesalpinia tinctoria, Caesalpinia pectinata u.a. |
| Cajanus cajan | Cytisus cajan, Cajanus bicolor, Cajanus flavus |
| Calibanus hookeri | Dasylirion hookeri, Nolina hookeri, Beaucarnea hookeri, Calibanus caespitosus |
| Calliandra brevipes | Calliandra selloi, Acacia selloi, Calliandra yucunensis |
| Calliandra emarginata | Inga emarginata |
| Calliandra eriophylla | Calliandra chamaedrys |
| Calliandra haematocephala | Anneslia haematocephala, Calliandra inaequilatera |
| Calliandra parvifolia | Calliandra bicolor, Calliandra falcifera, Calliandra microcalyx, Calliandra peckoltii |
| Calliandra pittieri | Anneslia pittieri |
| Calliandra schultzei | Calliandra riparia |
| Calliandra surinamensis | Anneslia fasciculata, Inga fasciculata |
| Callistemon sieberi | Callistemon pityoides |
| Calonyction album | Ipomoea alba, Calonyction aculeatum, Ipomoea bona-nox, Convolvulus aculeatus |
| Calopyxis grandidieri | Combretum grandidieri |
| Camellia japonica | Thea japonica |
| Camellia oleifera | Camellia drupifera, Camellia oleosa |
| Camellia sinensis | Thea sinensis |
| Campsis grandiflora | Bignonia chinensis |
| Campsis radicans | Bignonia radicans |
| Cananga odorata | Canangium fruticosum, Canangium odoratum, Unona odorata, Unona odorata, Uvaria odorata, Uvaria axillaris |
| Canarina canariensis | Canarina campanula |
| Canavalia ensiformis | Dolichos ensiformis |
| Canavalia maritima | Canavalia rosea |
| Canella winterana | Canella alba |
| Cardiospermum halicacabum | Cardiospermum microcarpum |
| Carica pubescens | Carica candamarcensis, Carica chiriquensis |
| Carica quercifolia | Vasconcella quercifolia, Carica acuata, Carica bonplandii, Carica hastaefolia, Carica hastata, Carica quercifolia, Vasconcella lanceolata |
| Carissa bispinosa | Carissa acuminata |
| Carissa grandiflora | Carissa macrocarpa |
| Cassia abbreviata | Cassia abbreviata var. granitica, |
| Cassia alata | Senna alata |
| Cassia angustifolia | Cassia acutifolia, Senna alexandrina |
| Cassia artemisoides | Senna artemisoides |
| Cassia bicapsularis | Senna bicapsularis, Cassia emarginata |
| Cassia biflora | Senna pallida |
| Cassia candolleana | Senna candolleana |
| Cassia covesii | Senna covesii, Senna polyantha |
| Cassia didymobotrya | Senna didymobotrya |
| Cassia eremophila | Senna nemophila |
| Cassia fasciculata | Chamaecrista fasciculata, Chamaecrista deeringiana, Cassia chamaecrista |
| Cassia floribunda | Senna x floribunda |
| Cassia helmsii | Senna helmsii |
| Cassia italica | Cassia obovata |
| Cassia multijuga | Senna multijuga |
| Cassia notabilis | Senna notabilis |
| Cassia occidentalis | Senna occidentalis |
| Cassia odorata | Senna odorata |
| Cassia pleurocarpa | Senna pleurocarpa |
| Cassia siamea | Senna siamea |
| Cassia singueana | Senna singueana |
| Cassia spectabilis | Senna spectabilis, Cassia carnaval |
| Cassia sturtii | Senna sturtii |
| Catalpa bignonioides | Catalpa syringaefolia, Bignonia catalpa |
| Cephalanthus occidentalis | Cephalanthus acuminatus, Cephalanthus berlandieri, Cephalanthus obtusifolius, Cephalanthus oppositifolius |
| Cercidium floridum | Cercidium torreyanum, Parkinsonia florida |
| Cercidium microphyllum | Parkinsonia microphylla |
| Cestrum nocturnum | Cestrum scandens, Cestrum foetidissimum, Chiococca nocturna, Cestrum hirtellum, Cestrum suberosum |
| Chimonanthus praecox | Chimonanthus fragrans, Calycanthus praecox |
| Chorisia speciosa | Ceiba speciosa |
| Chortolirion angolense | Haworthia angolensis |
| Cinnamomum camphora | Laurus camphora, Camphora officinarum |
| Cinnamomum zeylanicum | Cinnamomum verum |
| Cissus aralioides | Vitis aralioides |
| Cissus opaca | Vitis opaca |
| Cissus rotundifolia | Cissus quadrangularis, Saelanthus rotundifolius |
| Cissus tuberosa | Vitis tuberosa |
| Clausena anisata | Clausena abyssinica, Clausena inaequalis |
| Clavija longifolia | Clavija ornata, Theophrasta longifolia |
| Clerodendrum trichotomum | Clerodendrum fargesii, Clerodendrum koshunense, Clerodendrum yakusimense, Siphonanthus trichotomus, Siphonanthus yakusimensis |
| Clianthus formosus | Swainsonia formosa |
| Clivia miniata | Vallota miniata |
| Colocasia esculenta | Colocasia antiquorum var. esculenta, Caladium esculentum |
| Combretum fruticosum | Combretum aurantiacum, Combretum benthamianum, Combretum farinosum, Combretum formosum, Combretum gloriosum, Combretum micropetalum, Gaura fruticosa, Combretum loeflingii, u.v.a. |
| Cordyline australis | Dracaena australis |
| Cordyline indivisa | Dracaena indivisa |
| Cordyline terminalis | Dracaena terminalis |
| Coreopsis gigantea | Leptosyne gigantea, Tuckermannia gigantea |
| Corypha utan | Corypha elata |
| Couroupita guianensis | Couratari pedicellaris, Lecythis bracteata, Pekea couroupita |
| Cudrania tricuspidata | Maclura tricuspidata |
| Cyphomandra betacea | Cyphomandra crassicaulis, Solanum betaceum |
| Cyphostemma bainesii | Cissus bainesii, Vitis bainesii |
| Cyrtostachys renda | Cyrtostachys lakka |
