Last updated October 1, 2009
| Name | Family | Nativity |
| Caesalpinia cacalaco | Caesalpiniaceae | S Mexico |
| Caesalpinia sp. | Caesalpiniaceae | |
| Calamagrostis nutkaensis | Poaceae | Western United States |
| Calibanus hookeri | Nolinaceae | Mexico |
| Calibanus hybrid | Nolinaceae | |
| Calliandra sp. | Mimosaceae | |
| Callistemon citrinus cv. Jeffersii | Myrtaceae | Australia |
| Callistemon cv. Cane’s Hybrid | Myrtaceae | |
| Callistemon cv. Little John | Myrtaceae | |
| Callistemon montanus | Myrtaceae | E Australia |
| Callistemon pinifolius | Myrtaceae | Australia(New South Wales) |
| Callistemon salignus | Myrtaceae | SE Australia |
| Callistemon speciosus | Myrtaceae | W Australia |
| Callitris rhomboidea | Cupressaceae | Australia |
| Calocedrus decurrens | Cupressaceae | Oregon to California |
| Calodendrum capense | Rutaceae | |
| Calpurnia aurea ssp. aurea | Fabaceae | South Africa |
| Camellia cv. Yume | Theaceae | |
| Camellia japonica cv. | Theaceae | |
| Camellia japonica cv. Bob Hope | Theaceae | |
| Camellia japonica cv. C.M. Wilson | Theaceae | |
| Camellia japonica cv. Calypso | Theaceae | |
| Camellia japonica cv. Chandler Elegans Variegated | Theaceae | |
| Camellia japonica cv. Colonel Fiery | Theaceae | |
| Camellia japonica cv. Daijohkan | Theaceae | |
| Camellia japonica cv. Daikhjan | Theaceae | |
| Camellia japonica cv. Debutante | Theaceae | |
| Camellia japonica cv. Debutante Benten | Theaceae | |
| Camellia japonica cv. Elegans | Theaceae | |
| Camellia japonica cv. Herme | Theaceae | |
| Camellia japonica cv. Kramer Supreme | Theaceae | |
| Camellia japonica cv. Magnoliaeflora | Theaceae | |
| Camellia japonica cv. Moonlight Sonata | Theaceae | |
| Camellia japonica cv. Mrs. Charles Cobb | Theaceae | |
| Camellia japonica cv. Mrs. D.W. Davis | Theaceae | |
| Camellia japonica cv. Nuccio’s Pink Lace | ericacaea | |
| Camellia japonica cv. Pink Pagoda | Theaceae | |
| Camellia japonica cv. Shira Ogi | Theaceae | |
| Camellia japonica cv. Shiro Chan | Theaceae | |
| Camellia japonica cv. Zorina | Theaceae | |
| Camellia lutchuensis cv. Minato-No-Akebono | Theaceae | |
| Camellia lutchuensis cv. Minato-No-Haru | Theaceae | |
| Camellia lutchuensis cv. Tenju | Theaceae | |
| Camellia reticulata cv. Buddha | Theaceae | |
| Camellia reticulata cv. E.G. Waterhouse | Theaceae | |
| Camellia sasanqua cv. | Theaceae | |
| Camellia sasanqua cv. Choji Guruma | Theaceae | |
| Camellia sasanqua cv. Himekoki | Theaceae | |
| Camellia sasanqua cv. Showa-no-sakae | Theaceae | |
| Campanula poscharskyana | Campanulaceae | Europe |
| Campanula poscharskyana | Campanulaceae | N Yugoslavia |
| Campanula poscharskyana cv. Alba | Campanulaceae | Europe |
| Campylanthus salsoloides | Scrophulariaceae | Spain(Canary Islands) |
| Campyloneurum angustifolia | Polypodiaceae | Tropical America |
| Campyloneurum sp. | Polypodiaceae | |
| Campyloneurum xalapense | Polypodiaceae | Mexico |
| Canistrum cv. Leopardinum | Bromeliaceae | |
| Canistrum triangulare | Bromeliaceae | Brazil |
| Canistrum wendlandii | Bromeliaceae | |
| Canna cv. Pretoria | Cannaceae | |
| Canna hybrid | Cannaceae | |
| Canna x ehemanni | Cannaceae | |
| Canna x generalis cv. King Humbert | Cannaceae | |
| Cantua buxifolia | Polemoniaceae | Peru, Bolivia, N Chile |
| Capparis spinosa | Capparaceae | Greece |
| Carex albula | Cyperaceae | S Australia |
| Carex elata cv. Bowles Golden | Cyperaceae | |
| Carex glauca | Cyperaceae | Central Europe |
| Carex morrowii cv. Aurea-Variegata | Cyperaceae | |
| Carex muskingumensis | Cyperaceae | Central United States |
| Carex solandri | Cyperaceae | New Zealand |
| Carex spissa | Cyperaceae | California |
| Carica quercifolia | Caricaceae | South America |
| Carludovica palmata | Cyclanthaceae | Central and South America |
| Carnegeia gigantea | Cactaceae | United States, Mexico(Sonora) |
| Caryota mitis | Arecaceae | India to Philippines, Java |
| Caryota no | Arecaceae | Borneo |
| Caryota obtusa | Arecaceae | N India |
| Caryota ochlandra | Arecaceae | S China |
| Caryota rumphiana | Arecaceae | Australia, India, Philippines |
| Caryota sp | Arecaceae | Indonesia |
| Caryota sp. | Arecaceae | |
| Caryota urens | Arecaceae | |
| Caryota urens | Arecaceae | India, Sri Lanka, Malay Penn. |
| Cassia excelsa | Caesalpiniaceae | E Brazil |
| Castanea cv. Colossal | Fagaceae | |
| Casuarina cristata | Casuarinaceae | Australia |
| Casuarina equisetifolia | Casuarinaceae | Australia |
| Catalpa speciosa | Bignoniaceae | E United States |
| Cattleya cv. Sue Ozella | Orchidaceae | |
| Ceanothus arboreus | Rhamnaceae | |
| Ceanothus arboreus | Rhamnaceae | Channel Islands, CA |
| Ceanothus arboreus | Rhamnaceae | Is. off California coast |
| Ceanothus cuneatus | Rhamnaceae | Oregon to Baja, CA |
| Ceanothus cv. Centennial | Rhamnaceae | |
| Ceanothus cv. Concha | Rhamnaceae | |
| Ceanothus cv. Dark Star | Rhamnaceae | |
| Ceanothus cv. Ray Hartman | Rhamnaceae | |
| Ceanothus gloriosus cv. Anchor Bay | Rhamnaceae | |
| Ceanothus griseus v. horizontalis cv. Yankee Point | Rhamnaceae | |
| Ceanothus griseus v. horizontalis cv. Yankee Point | Rhamnaceae | California |
| Ceanothus impressus | Rhamnaceae | Coastal Cen California |
| Ceanothus spinosus | Rhamnaceae | California and Mexico |
| Ceanothus thyrsiflorus | Rhamnaceae | California to S Oregon |
| Ceaonthus cultivars | Rhamnaceae | |
| Cedrela sinensis | Meliaceae | China |
| Cedrus atlantica | Pinaceae | Algeria |
| Cedrus atlantica cv. Glauca | Pinaceae | |
| Cedrus atlantica cv. Glauca Pendula | Pinaceae | |
| Cedrus deodara | Pinaceae | Himalayas |
| Ceiba pentandra | Bombacaceae | Mexico |
| Centranthus ruber | Valerianaceae | Mediterranean |
| Cephalocereus senilis | Cactaceae | Mexico |
| Ceratophyllum demersum | Ceratophyllaceae | Worldwide |
| Ceratostigma plumbaginoides | Plumbaginaceae | W China |
| Ceratozamia beccarae | Zamiaceae | Mexico(Tabasco) |
| Ceratozamia hildae | Zamiaceae | Mexico |
| Ceratozamia kuesteriana | Zamiaceae | Mexico(Tamaulipas) |
| Ceratozamia latifolia | Zamiaceae | Mexico |
| Ceratozamia mexicana | Zamiaceae | Mexico |
| Ceratozamia microstrobila | Zamiaceae | Mexico |
| Ceratozamia microstrobila x sp. aff. mexicana | Zamiaceae | |
| Ceratozamia miqueliana | Zamiaceae | Mexico(Veracruz) |
| Ceratozamia miqueliana “Malpaso” | Zamiaceae | Mexico |
| Ceratozamia mixeorum | Zamiaceae | Mexico(Oaxaca) |
| Ceratozamia morettii | Zamiaceae | Mexico(Veracruz) |
| Ceratozamia norstogii | Zamiaceae | Mexico |
| Ceratozamia robusta | Zamiaceae | Mexico, Belize & Guatemala |
| Ceratozamia sabatoi | Zamiaceae | Mexico |
| Ceratozamia soconuscensis | Zamiaceae | Mexico(Chiapas) |
| Ceratozamia sp. | Zamiaceae | |
| Ceratozamia sp. nov. “Jalapa” | Zamiaceae | Mexico(Veracruz) |
| Ceratozamia sp. nov. “Naranjal” | Zamiaceae | Mexico(Veracruz) |
| Ceratozamia sp. nov. “Puerto Escondido” | Zamiaceae | Mexico |
| Ceratozamia sp. nov. “Xilitla” | Zamiaceae | |
| Ceratozamia whitelockiana | Zamiaceae | Mexico(Oaxaca) |
| Ceratozamia zaragozae | Zamiaceae | Mexico(San Luis Potosi) |
| Ceratozamia zoquorum | Zamiaceae | Mexico(Chiapas) |
| Cercidiphyllum japonicum | Cercidiphyllaceae | China, Japan |
| Cercidium cv. Desert Museum | Fabaceae | |
| Cercis occidentalis | Fabaceae | CA, AZ, UT |
| Cereus “labouritanus” | Cactaceae | |
| Cereus aethiops | Cactaceae | N. Argentina, S. Brazil |
| Cereus alacriportanus | Cactaceae | Brazil, Uruguay, Paraguay |
| Cereus cf. huntingtonianus | Cactaceae | |
| Cereus collosus | Cactaceae | Brazil |
| Cereus comarapanus | Cactaceae | Bolivia(Santa Cruz) |
| Cereus formosus | Cactaceae | Brazil |
| Cereus glaucus | Cactaceae | Unknown |
| Cereus hankeanus | Cactaceae | Argentina, Bolivia |
| Cereus hildmannianus | Cactaceae | Brazil, Arg., Paraguay, Urug. |
| Cereus huilunchu | Cactaceae | Bolivia(Cochabamba) |
| Cereus hybrid | Cactaceae | |
| Cereus hybrid f. monstrosus | Cactaceae | |
| Cereus jamacaru | Cactaceae | Brazil |
| Cereus jamacaru f. monstrosus | Cactaceae | Brazil |
| Cereus lamprospermus ssp. colosseus | Cactaceae | Bolivia |
| Cereus micropetalis | Cactaceae | Bolivia |
| Cereus peruvianus f. monstrosus | Cactaceae | SE South America |
| Cereus peruvianus v. persicinus | Cactaceae | |
| Cereus peruvianus v. reclinatus | Cactaceae | |
| Cereus repandus | Cactaceae | Venezuela, W Caribbean |
| Cereus sp. | Cactaceae | |
| Cereus sp. | Cactaceae | Bolivia |
| Cereus stenogonus | Cactaceae | Argentina, Paraguay |
| Cereus validus | Cactaceae | E Bolivia, Argentina |
| Cereus vargasianus | Cactaceae | Peru |
| Cereus variabilis | Cactaceae | Brazil |
| Cereus variabilis f. monstrosus | Cactaceae | Brazil |
| Ceropegia dichotoma | Asclepiadaceae | |
| Ceropegia dichotoma | Asclepiadaceae | Spain(Canary Islands) |
| Ceropegia fusca | Asclepiadaceae | Spain(Canary Islands) |
| Ceroxylon quindiuense | Arecaceae | Colombia |
| Cestrum elegans | Solanaceae | American Tropics |
| Chamaecyparis lawsoniana | Cupressaceae | SW California to NW Oregon |
| Chamaecyparis nidifera cv. Nestoides | Cupressaceae | |
| Chamaecyparis obtusa cv. Ericoides | Cupressaceae | |
| Chamaecyparis obtusa cv. Gracilis | Cupressaceae | |
| Chamaecyparis obtusa cv. Kosteri | Cupressaceae | |
| Chamaecyparis obtusa cv. Nana Gracilis | Cupressaceae | |
| Chamaecyparis obtusa cv. Reis Dwarf | Cupressaceae | |
| Chamaecyparis pisifera cv. Cyano-viridis | Cupressaceae | |
| Chamaecyparis sp. | Cupressaceae | |
| Chamaedorea allenii | Arecaceae | Panama |
| Chamaedorea alternans | Arecaceae | Mexico(Veracruz) |
| Chamaedorea arenbergiana | Arecaceae | Mexico to Guatemala & Honduras |
| Chamaedorea brachypoda | Arecaceae | Guatemala, Honduras |
| Chamaedorea carchensis | Arecaceae | Mexico, Guatemala |
| Chamaedorea cataractarum | Arecaceae | S Mexico |
| Chamaedorea costaricana | Arecaceae | Costa Rica, Nicaragua,Honduras |
| Chamaedorea cv. Irving Cantor | Arecaceae | |
| Chamaedorea elatior | Arecaceae | |
| Chamaedorea elatior | Arecaceae | Mexico, Guatemala |
| Chamaedorea elegans | Arecaceae | Mexico, Guatemala, Belize |
| Chamaedorea ernesti-augustii | Arecaceae | Belize |
| Chamaedorea ernesti-augustii | Arecaceae | Mexico to Honduras |
| Chamaedorea falcifera | Arecaceae | |
| Chamaedorea fragrans | Arecaceae | Peru |
| Chamaedorea geonomiformis | Arecaceae | Mexico to Honduras |
| Chamaedorea glaucifolia | Arecaceae | Mexico(Chiapas) |
| Chamaedorea hooperiana | Arecaceae | Mexico(Veracruz) |
| Chamaedorea klotzschiana | Arecaceae | Mexico(Veracruz) |
| Chamaedorea linearis | Arecaceae | Venezuela to Bolivia |
| Chamaedorea metallica | Arecaceae | Mexico |
| Chamaedorea microspadix | Arecaceae | Mexico |
| Chamaedorea nationsiana | Arecaceae | Guatemala |
| Chamaedorea neurochlamys | Arecaceae | S Mexico to Honduras |
| Chamaedorea nubium | Arecaceae | Mexico, Guatemala, El Salvador |
| Chamaedorea oblongata | Arecaceae | Mexico to Nicaragua |
| Chamaedorea pedunculata | Arecaceae | Costa Rica(Puntarenas) |
| Chamaedorea pinnatifrons | Arecaceae | Mexico to South America |
| Chamaedorea plumosa | Arecaceae | Mexico |
| Chamaedorea pochutlensis | Arecaceae | W Mexico |
| Chamaedorea quezallteca | Arecaceae | Mexico(Chiapas) to Honduras |
| Chamaedorea radicalis | Arecaceae | Mexico |
| Chamaedorea rhizomatosa | Arecaceae | Mexico(Oaxaca) |
| Chamaedorea rojasiana | Arecaceae | Mexico(Chiapas), Guatemala |
| Chamaedorea rossteniorum | Arecaceae | Costa Rica, Panama |
| Chamaedorea sartorii | Arecaceae | Mexico, Honduras |
| Chamaedorea schiedeana | Arecaceae | Mexico |
| Chamaedorea seifrizii | Arecaceae | S Mexico to Honduras |
| Chamaedorea sp. | Arecaceae | |
| Chamaedorea stolonifera | Arecaceae | Mexico(Chiapas) |
| Chamaedorea tenella | Arecaceae | Mexico, Costa Rica |
| Chamaedorea tepejilote | Arecaceae | SE Mexico to N Colombia |
| Chamaedorea warscewiczii | Arecaceae | Panama, Costa Rica |
| Chamaedorea woodsoniana | Arecaceae | Mexico, Cen America |
| Chamaerops humilis | Arecaceae | S Europe & N Africa |
| Chambeyronia macrocarpa | Arecaceae | New Caledonia |
| Chambeyronia sp. | Arecaceae | |
| Cheiridopsis candidissima | Aizoaceae | South Africa |
| Chilopsis linearis | Bignoniaceae | SW US to N Mexico |
| Chimonanthus praecox | Calycanthaceae | China |
| Chimonobambusa quadrangularis | Poaceae | China |
| Chlorophytum comosum cv. Variegatum | Liliaceae | |
| Chondropetalum elephantinum | Restionaceae | Africa |
| Chorisia speciosa | Bombacaceae | Argentina, Brazil |
| Chrysanthemum coccineum | Asteraceae | |
| Chrysanthemum paludosum | Asteraceae | W Mediterranean |
| Chusquea aff. culeou | Poaceae | Chile |
| Chusquea coronalis | Poaceae | Central America |
| Cibotium glaucum | Dicksoniaceae | Hawaii |
| Cibotium schiedei | Dicksoniaceae | Mexico, Guatemala |
| Cinnamomum camphora | Lauraceae | China, Taiwan, Japan |
| Cinnamomum zeylanicum | Lauraceae | India, Sri Lanka, Myanmar |
| Cipocereus sp. | Cactaceae | Brazil |
| Cissus tuberosa | Vitaceae | Mexico |
| Cistanthe grandiflora cv. Jazz Time | Portulacaceae | |
| Cistus cv. Sunset | Cistaceae | |
| Cistus salviifolius cv. Prostratus | Cistaceae | Europe |
| Cistus sp. | Cistaceae | |
| Citrus aurantifolia | Rutaceae | |
| Citrus aurantifolia cv. Bearss | Rutaceae | |
| Citrus junos | Rutaceae | Japan |
| Citrus limettioides | Rutaceae | India |
| Citrus limon | Rutaceae | |
| Citrus limon cv. Eureka | Rutaceae | |
| Citrus limon cv. Meyer | Rutaceae | |
| Citrus limon cv. Pink Lemonade | Rutaceae | |
| Citrus paradisi x maxima cv. Oroblanco | Rutaceae | |
| Citrus reticulata | Rutaceae | |
| Citrus reticulata cv. Dancy | Rutaceae | |
| Citrus reticulata cv. Pixie | Rutaceae | |
| Citrus reticulata cv. Satsuma | Rutaceae | |
| Citrus reticulata cv. Willowleaf | Rutaceae | |
| Citrus sinensis | Rutaceae | |
| Citrus sinensis cv. “Agua Tibia” | Rutaceae | |
| Citrus sinensis cv. Cara Cara | Rutaceae | |
| Citrus sinensis cv. Robertson | Rutaceae | |
| Citrus sinensis cv. Satsuma | Rutaceae | |
| Citrus x paradisi cv. Rio Red | Rutaceae | |
| Cleistocactus acanthurus | Cactaceae | Peru |
| Cleistocactus baumannii | Cactaceae | South America |
| Cleistocactus baumannii v. chacoanus | Cactaceae | Bolivia |
| Cleistocactus brookeae | Cactaceae | Bolivia |
| Cleistocactus buchtienii | Cactaceae | Bolivia |
| Cleistocactus ferrarii | Cactaceae | Argentina |
| Cleistocactus fieldianus | Cactaceae | Peru |
| Cleistocactus fieldianus ssp. tessallatus | Cactaceae | Peru |
| Cleistocactus hyalacanthus | Cactaceae | Argentina |
| Cleistocactus hybrid | Cactaceae | |
| Cleistocactus icosagonus | Cactaceae | S Ecuador, N Peru |
| Cleistocactus laniceps | Cactaceae | Bolivia |
| Cleistocactus micropetalus | Cactaceae | Peru |
| Cleistocactus morawetzianus | Cactaceae | Peru |
| Cleistocactus otoyensis | Cactaceae | |
| Cleistocactus palhuayensis | Cactaceae | Bolivia |
| Cleistocactus parviflorus | Cactaceae | Bolivia |
| Cleistocactus plagiostoma | Cactaceae | Peru |
| Cleistocactus ritteri | Cactaceae | Bolivia |
| Cleistocactus samaipatanus | Cactaceae | Bolivia, Peru |
| Cleistocactus sepium | Cactaceae | Ecuador |
| Cleistocactus sepium v. cristatum | Cactaceae | Ecuador |
| Cleistocactus smaragdiflorus | Cactaceae | Argentina, Bolivia, Paraguay |
| Cleistocactus sp. | Cactaceae | |
| Cleistocactus sucrensis v. tupizensis | Cactaceae | Bolivia |
| Cleistocactus tominensis | Cactaceae | Bolivia |
| Cleistocactus tupizensis | Cactaceae | Bolivia |
| Cleistocactus x Oreocereus hybrid | Cactaceae | |
| Clematis armandii | Ranunculaceae | Cen & W China |
| Clematis ligusticifolia | Ranunculaceae | W North America |
| Clerodendrum bungei | Verbenaceae | China |
| Clerodendrum trichotomum | Verbenaceae | Japan |
| Cleyera japonica | Theaceae | Japan and SE Asia |
| Clivia Belgian hybrids | Amaryllidaceae | South Africa |
| Clivia caulescens | Amaryllidaceae | South Africa |
| Clivia hybrid | Amaryllidaceae | |
| Clivia miniata | Amaryllidaceae | South Africa |
| Clusia rosea | Clusiaceae | Fla., Mex. to S.Am.,W. Indies |
| Clusia sp. | Clusiaceae | |
| Coccothrinax alta | Arecaceae | Puerto Rico, Virgin Islands |
| Coccothrinax crinita | Arecaceae | Cuba |
| Cocculus laurifolius | Menispermaceae | Himalayas |
| Cochemiea halei | Cactaceae | Mexico(Baja California) |
| Cochemiea poselgeri | Cactaceae | Mexico(Baja California Sur) |
| Cochlospermum vitifolium | Bixaceae | Tropical America |
| Coffea arabica | Rubiaceae | Ethiopia, Sudan |
| Coleonema album | Rutaceae | South Africa |
| Coleonema pulchrum | Rutaceae | South Africa |
| Coleus barbatus | Lamiaceae | South Africa |
| Coleus x hybridus cv. Kong | Lamiaceae | |
| Colocasia esculenta | Araceae | Tropical E Asia |
| Colocasia esculenta cv. | Araceae | |
| Colocasia esculenta cv. Black Magic | Araceae | |
| Colocasia esculenta cv. Fontanesii | Araceae | |
| Colocasia esculenta v. antiquorum | Araceae | India |
| Combretum erythrophyllum | Combretaceae | South Africa |
| Combretum fruticosum | Combretaceae | Mozambique |
| Combretum zeyheri | Combretaceae | SE Africa |
| Commiphora grandifolia | Vitaceae | Madagascar |
| Coniogramme japonica | Pteridaceae | China, Taiwan, Korea, Japan |
| Consolea moniliformis | Cactaceae | Cuba |
| Consolea nashii | Cactaceae | Bahamas, Cuba |
| Convolvulus cneorum | Convolvulaceae | Italy |
| Copernicia alba | Arecaceae | South America |
| Copiapoa cinerea | Cactaceae | Chile |
| Copiapoa coquimbana | Cactaceae | Chile |
| Copiapoa fiedleriana | Cactaceae | Chile(Atacama) |
| Copiapoa haseltoniana | Cactaceae | Chile |
| Copiapoa humilis | Cactaceae | N Chile |
| Copiapoa krainziana | Cactaceae | Chile |
| Copiapoa marginata | Cactaceae | Chile(Atacama) |
| Copiapoa montana | Cactaceae | N Chile |
| Copiapoa sp. | Cactaceae | |
| Copiapoa tenuissima | Cactaceae | Chile |
| Cordyline australis cv. Red Sensation | Agavaceae | |
| Cordyline rubra | Agavaceae | Cultivated orign |
| Cordyline sp. | Agavaceae | |
| Cordyline stricta | Agavaceae | Australia |
| Cordyline terminalis | Agavaceae | E Asia |
| Cordyline terminalis cv. Bolero Bicolor | Agavaceae | |
| Coreopsis basalis | Asteraceae | United States(Texas) |
| Coreopsis grandiflora | Asteraceae | E & S United States |
| Coreopsis grandiflora cv. Early Sunrise | Asteraceae | |
| Cornus florida | Cornaceae | |
| Cornus florida cv. Cloud Nine | Cornaceae | |
| Cornus sanguinea | Cornaceae | Europe |
| Corokia sp. | Cornaceae | |
| Correa cv. Dusky Bells | Rutaceae | |
| Correa cv. Ivory Bells | Rutaceae | |
| Correa pulchella | Rutaceae | Australia |
| Correa pulchella | Rutaceae | S Australia |
| Corryocactus apiciflorus | Cactaceae | Peru |
| Corryocactus pulquiensis | Cactaceae | Bolivia(Santa Cruz) |
| Corryocactus sp. | Cactaceae | |
| Corynocarpus laevigatus | Corynocarpaceae | New Zealand |
| Corynocarpus laevigatus cv. Variegata | Corynocarpaceae | |
| Coryphantha compacta | Cactaceae | Mexico |
| Coryphantha elephantidens | Cactaceae | Mexico (Michoacan) |
| Coryphantha radians | Cactaceae | Mexico |
| Cotoneaster dammeri cv. Lowfast | Rosaceae | |
| Cotoneaster lacteus | Rosaceae | China |
| Cotyledon adscendens | Crassulaceae | South Africa |
| Cotyledon orbiculata | Crassulaceae | South Africa |
| Cotyledon orbiculata v. flanaganii | Crassulaceae | South Africa(E. Cape Prov.) |
| Cotyledon sp. | Crassulaceae | |
| Cotyledon tomentosa ssp. ladismithiensis | Crassulaceae | South Africa |
| Cotyledon tomentosa ssp. tomentosa | Crassulaceae | South Africa |
| Cotyledon undulata | Crassulaceae | South Africa(E. Cape Province) |
| Cotyledon woodii f. | Crassulaceae | South Africa |
| Crassula alba cv. Rep-tiles | Crassulaceae | |
| Crassula arborescens | Crassulaceae | South Africa |
| Crassula arborescens ssp. undulatifolia | Crassulaceae | Mexico |
| Crassula argentea | Crassulaceae | Mexico |
| Crassula cv. Red Flame | Crassulaceae | |
| Crassula falcata | Crassulaceae | South Africa |
| Crassula multicava | Crassulaceae | E South Africa |
| Crassula orbicularis | Crassulaceae | South Africa |
| Crassula ovata | Crassulaceae | South Africa |
| Crassula ovata cv. Gollum | Crassulaceae | |
| Crassula perfoliata v. perfoliata | Crassulaceae | South Africa(E. Cape Prov.) |
| Crassula perforata | Crassulaceae | South Africa |
| Crassula phyturus | Crassulaceae | African Tropics |
| Crassula sarcocaulis | Crassulaceae | South Africa(Mpumulanga) |
| Crassula sp. | Crassulaceae | |
| Crassula sp. nov. “Matsikamma Mountains” | Crassulaceae | |
| Crassula streyi | Crassulaceae | South Africa(KwaZulu-Natal) |
| Crassula tetragona ssp. acutifolia | Crassulaceae | South Africa |
| Crataegus sp. | Rosaceae | |
| Crinum asiaticum cv. | Amaryllidaceae | |
| Crotalaria capensis | Papilionaceae | SE Africa |
| Croton sylvaticus | Euphorbiaceae | South Africa |
| Cryosophila sp. | Arecaceae | Mexico |
| Cryptanthus burle-marxii | Bromeliaceae | Brazil |
| Cryptanthus cv. Madame Ganna Walska | Bromeliaceae | |
| Cryptbergia rubra | Bromeliaceae | |
| Cryptomeria japonica | Taxodiaceae | Japan |
| Cryptomeria japonica cv. Elegans | Taxodiaceae | |
| Cryptomeria japonica v. sinensis | Taxodiaceae | |
| Ctenanthe sp. | Marantaceae | Brazil |
| Cunninghamia lanceolata | Taxodiaceae | China |
| Cuphea caeciliae | Lythraceae | Mexico |
| Cuphea micropetala | Lythraceae | Mexico |
| Cupressus cashmeriana | Cupressaceae | Kashmir, Tibet |
| Cupressus dupreziana | Cupressaceae | SE Algeria |
| Cupressus funebris | Cupressaceae | China, East Asia |
| Cupressus macrocarpa | Cupressaceae | California |
| Cupressus sempervirens | Cupressaceae | Europe and Asia |
| Curculigo capitulata | Hypoxidaceae | Asian Tropics, Polynesia |
| Cussonia paniculata | Araliaceae | South Africa |
| Cussonia spicata | Araliaceae | South Africa to Zambia |
| Cycas armstrongii | Cycadaceae | Australia(N. Territory) |
| Cycas cairnsiana forma nov. “Mt. Surprise” | Cycadaceae | |
| Cycas cf. rumphii | Cycadaceae | Indonesia |
| Cycas circinalis | Cycadaceae | Burma, India, Thailand |
| Cycas couttsiana | Cycadaceae | Australia(Queensland) |
| Cycas debaoensis | Cycadaceae | China |
| Cycas media | Cycadaceae | Australia(Queensland) |
| Cycas neo-caledonica | Cycadaceae | New Caledonia |
| Cycas revoluta | Cycadaceae | China,Japan,Japan(Ryukyu Is.) |
| Cycas riuminiana | Cycadaceae | Philippines(Luzon) |
| Cycas rumphii | Cycadaceae | Indonesia |
| Cycas schumanniana | Cycadaceae | Papua New Guinea |
| Cycas scratchleyana | Cycadaceae | Papua New Guinea |
| Cycas sp. | Cycadaceae | |
| Cycas sp. nov. “India” | Cycadaceae | India |
| Cycas sp. nov. “Malaysia” | Cycadaceae | NW Malaysia |
| Cycas sp. nov. “Petford Dwarf” | Cycadaceae | |
| Cycas taitungensis | Cycadaceae | Taiwan |
| Cycas taiwaniana | Cycadaceae | Taiwan, SE China |
| Cycas thouarsii | Cycadaceae | E. Africa & Indian Ocean Is. |
| Cycas wadei | Cycadaceae | Philippines(Culion) |
| Cycas yorkiana | Cycadaceae | Australia(Queensland) |
| Cymbalaria muralis | Scrophulariaceae | Europe |
| Cymbidium iridiodes | Orchidaceae | IndoChina |
| Cymbidium lowianum v. concolor | Orchidaceae | |
| Cyperus alternifolius | Cyperaceae | Madagascar |
| Cyperus papyrus | Cyperaceae | Tropical & N Africa |
| Cyperus textilis | Cyperaceae | |
| Cyphostemma juttae | Vitaceae | Namibia |
| Cyrtomium falcatum | Polypodiaceae | Asia, South Africa |
| Cyrtomium falcatum cv. Rochfordianum | Polypodiaceae |
