| C |
| Cabert miscanthus, Miscanthus sinensis var. condensatus 'Cabaret' |
| Caladium, Caladium |
| Calendula (Pot marigold), Calendula officinalis |
| Calla lily, Zantedeschia spp. |
| Camas, Camassia |
| Camass, Camassia cusickii, C. esculenta |
| Camellia, Mountain, Stewartia ovata |
| Camellia, Silky, Stewartia malacodendron |
| Canadian mayflower, Maianthemum canadense |
| Canary bird flower, Tropaeolum peregrinum |
| Canary creeper, Tropaeolum peregrinum |
| Canary Island ivy, Hedera canariensis |
| Cancer corn, Conopholis americana |
| Candytuft (annual), Iberis amara, I. umbellata |
| Candytuft, Evergreen, Iberis sempervirens |
| Candytuft, Iberis sempervirens |
| Canna lily, Canna x generalis |
| Canna, Canna |
| Cape flower, Nerine bowdenii |
| Cape honeysuckle, Tecomaria capensis |
| Cape tulip, Haemanthus = Scadoxus |
| Cape hyacinth, Galtonia candicans |
| Caraway, Carum carvi |
| Cardinal climber, Ipomoea x multifida |
| Cardinal flower, Lobelia cardinalis |
| Carex, Carex spp. |
| Carolina cherry laurel, Prunus caroliniana |
| Carolina jasmine, Gelsemium sempervirens |
| Cast iron plant, Aspidistra elatior |
| Castor bean, Ricinus communis |
| Castor aralia, Kalopanax pictus |
| Catalpa, Catalpa spp. |
| Catalpa, Northern, Catalpa speciosa |
| Catalpa, Southern, Catalpa bignonioides |
| Cathedral bells, Cobaena scandens |
| Catherine wheel, Haemanthus = Scadoxus |
| Catmint, Nepeta spp. |
| Catnip, Nepta cataria |
| Cedar of Lebanon, Cedrus libani |
| Cedar, Atlantic white, Chamaecyparis thyoides |
| Cedar, Atlas, Cedrus atlantica |
| Cedar, Blue Atlas, Cedrus atlantica 'Glauca' |
| Cedar, California incense, Calocedrus decurrens |
| Cedar, Deodar, Cedrus deodara |
| Cedar, Eastern red, Juniperus virginiana |
| Cedar, Incense, Calocedrus decurrens |
| Cedar, Japanese, Cryptomeria japonica |
| Ceder, Western red, Thuja plicata |
| Cedrela, Chinese, Cedrela sinsensis = Toona sinensis |
| Celosia, Celosia crista |
| Chamomile, Chamaemelum nobile |
| Chamomile, Sweet false, Matricaria recutita |
| Chastetree, Vitex agnus-castus |
| Cherokee rose, Rosa laevigata |
| Cherry, Autumn blooming, Prunus subhirtella 'Autumnalis' |
| Cherry, Black, Prunus serotina |
| Cherry, Fire; Pin cherry, Prunus pennsylvanica |
| Cherry, Higan, Prunus subhirtella |
| Cherry, Japanese, Prunus serrulata |
| Cherry, Okame, Prunus x incamp 'Okame' |
| Cherry, Purple-leaf sand, Prunus x cistena |
| Cherry, Sargent, Prunus sargentii |
| Cherry, Ukon, Prunus serrulata 'Ukon' |
| Cherry, Wild; Black cherry, Prunus serotina |
| Cherry, Yoshino, Prunus x yedoensis |
| Cherry; Wild Black, Prunus serotina |
| Cherrylaurel, Carolina, Prunus caroliniana |
| Cherrylaurel, Portuguese, Prunus lusitonica |
| Chervil, Anthriscus cerefolium |
| Chestnut, American, Castanea dentata |
| Chicory, Cichorium intybus |
| Chilean glory flower, Eccremocarpus scaber |
| Chinaberry, Melia azadarach |
| Chinese flame tree, Koelreuteria bipinnata |
| Chinese gooseberry, Actinidia chinensis |
| Chinese parasol tree, Firmiana simplex |
| Chinese toon; Chinese cedrela, Cedrela sinsensis = Toona sinensis |
| Chinquapin, Castanea pumila |
| Chives, Allium schoenoprasum |
| Chokeberry, Red, Aronia arbutifolia |
| Chokecherry, Common, Prunus virginia |
| Christmas bells, Sandersonia aurantiaca |
| Chrysanthemum, Chrysanthemum morifolium |
| Cinquefoil, Five fingers, Potentilla, Potentilla spp. |
| Cinquefoil, Potentilla x hybrida |
| Clary sage, Salvia sclarea |
| Clematis hybrids, Clematis hybrida |
| Clematis, Italian , Clematis viticella |
| Clematis, Leather flower; Virgin's bower, Clematis spp. |
| Clematis, Scarlet, Clematis texensis, Clematis coccinea |
| Clematis, Anemone, Clematis montana |
| Clematis, Armand, Clematis armandii |
| Clematis, Jackman, Clematis x jackmanii |
| Clematis, Sweet autumn, Clematis paniculata, Clematis maximonowicziana |
| Clematis, Virgin's bower, Clematis virginiana |
| Cleome, Cleome hasslerana |
| Clethra, Cinnamonbark; Mountain pepperbush, Clethra acuminata |
| Clethra, Summersweet, Sweet pepperbush, Clethra alnifolia |
| Climbing fig, Ficus pumila |
| Climbing Lily, Gloriosa |
| Clock vine, Thunbergia alata |
| Cockscomb, Celosia crista |
| Coleus, Coleus x hybridus |
| Columbine, Wild, Aquilegia canadensis |
| Common yarrow, Achillea millefolium |
| Compact white-striped bamboo, Pleiodlastus variegatus |
| Compact zebra grass, Miscanthus sisnensis 'Hinjo' (Little Mickey) |
| Cone-flower, Purple, Echinacea purpurea |
| Coppertip, Crocosmia hybrids |
| Coppertip, Montbretia = Croscosmia |
| Coral bells, Cobaena scandens |
| Coral bells, Heuchera sanguinea |
| Coral drops, Bessera |
| Coral vine, Antigonon leptopus |
| Coral-beads, Carolina moonseed, Cocculus carolina |
| Coreopsis, Coreopsis spp. |
| Coreopsis, Threadleaf, Coreopsis verticillata |
| Coreopsis, Lanceleaf, Coreopsis lanceolata |
| Coriander (Cilantro), Coriandrum sativum |
| Corktree, Amur, Phelloendro amurense |
| Corktree, Chinese, Phellodendron chinese |
| Corktree, Sakhalin, Phellodendron sachalinense |
| Corn flower, Ixia hybrids |
| Cosmopolitan, Miscanthus sinensis var. Condensatus 'Cosmopolitan' |
| Cosmos, Cosmos spp. |
| Costmary, Chrysanthemum balsamita |
| Cotoneaster, Bearberry, Cotoneaster dammeri |
| Cotoneaster, Rockspray, Cotoneaster horizontalis |
| Cotoneaster, Willowleaf, Cotoneaster salicifolius 'Repens' |
| Cottonwood, Eastern; Eastern poplar, Populus deltoides |
| Crabapple, Parkman, Malus halliana var. parkmanii |
| Crabapple, Siebold, Malus sieboldii |
| Crabapple, Southern, Malus angustifolia |
| Crabapple, Tea, Malus hupehensis |
| Crabapple, Yunnan, Malus yunnanensis |
| Crabapples, Hybrid, Malus hybrids |
| Crabapples, Malus hybrids |
| Cranberry, Vaccinum macrocarpon |
| Cranesbill geranium, Geranium sanguineum |
| Crapemyrtle, Japanese, Lagerstroemia fauriei |
| Crapemyrtle, Lagerstroemia indica |
| Creeping broad leafed sedge, Carex siderosticha |
| Creeping fig, Ficus pumila |
| Crinodonna, x Crinodonna corsii(x Americana) |
| Crinum, Crinum |
| Crocosmia, Crocosmia x crocosmiiflora |
| Crocosmia, Montbretia = Croscosmia |
| Crocus, Autumn, Colchicum autumnale |
| Crocus, Dutch , Crocus spp. |
| Crocus, Fall Colchicum autumnale |
| Crocus, Fall, Crocus (Autumn Species) |
| Crocuses, Species, Crocus spp. (Spring flowering) |
| Cross vine, Bignonia capreolata, Doxantha capreolata |
| Crown Imperials, Fritillaria imperialis |
| Cruel vine, Araujia sericifera |
| Cryptomeria, Japanese, Cryptomeria japonica |
| Cryptomeria, Taiwan, Taiwania cryptomerioides |
| Cucumber tree, Magnolia acuminata |
| Cumberland rosemary, Conradina verticillata |
| Cup-and-saucer vine, Cobaena scandens |
| Cypress vine, Ipomea quamoclit, Quamoclit pennata |
| Cypress, Bald, Taxodium distichum |
| Cypress, Italian, Cupressus sempervirens |
| Cypress, Mexican swamp, Taxodium distichum var. mexicana = T. mucronatum |
| Cypress, Pond, Taxodium ascends = T. distichum var. nutans |
| Cypress, Pond, Taxodium DVdistichum var. imbricarium |
| Cypress, Siberian carpet grass; Russian arborvitae, Microbiota decussata |
| Cypress, Leyland, x Cupressocyparis leylandii |