Corydalis aurea Corydalis micrantha
Corylus americana Coryphantha elephantidens
Coryphantha erecta Cosmos atrosanguineus
Cosmos bipinnatus Cosmos bipinnatus 'Early Wonder'
Cosmos bipinnatus 'Sonata White' Cosmos sulphureus
Cosmos sulphureus 'Cosmic Orange' Cosmos sulphureus 'Cosmic Yellow'
Cosmos sulphureus 'Ladybird Scarlet' Cosmos sulphureus 'Lemon Twist'
Cosmos sulphureus 'Sunny Red' Costus pictus
Costus pulverulentus Cotinus obovatus
Coursetia glandulosa Crataegus aestivalis
Crataegus crus-galli Crataegus crus-galli 'Hooks'
Crataegus crus-galli var. inermis Crataegus mollis
Crataegus paucispina Crataegus phaenopyrum
Crataegus punctata Crataegus viridis 'Winter King'
Crinum americanum Crossopetalum ilicifolium
Cucurbita palmata Cuphea hyssopifola
Cuphea ignea Cuphea lanceolata
Cupressus arizonica 'Blue Pyramid' Cupressus arizonica var. arizonica
Cupressus arizonica var. glabra 'Blue Ice' Cupressus arizonica var. glabra 'Carolina Safire'
Cupressus arizonica var. glabra 'Gareei' Cupressus bakeri ssp. mathewsii
Cupressus guadalupensis Cupressus macrocarpa
Cupressus macrocarpa 'Gold Pillar' Cupressus macrocarpa 'Keown'
Cupressus macrocarpa 'Lutea' Cypripedium acaule
Cypripedium calceolus Cypripedium reginae
Cyrilla arida Cyrilla racemiflora
Dahlia Dahlia 'Big Hummer'
Dahlia 'Bishop of Llandaff' Dahlia 'Bloodstone'
Dahlia 'Border Princess' Dahlia 'Camano Choice'
Dahlia 'Elise Huston' Dahlia 'Ferncliff Flamingo'
Dahlia 'Figaro Improved' Dahlia 'Harlequin Mix'
Dahlia 'Harvest Amanda' Dahlia 'Paratola Sunrise'
Dahlia 'Red Pygmy' Dahlia 'Red Riding Hood'
Dahlia 'Rigoletto' Dahlia 'Thomas Edison'
Dalea capitata Dalea greggii
Dalea purpurea Dalea schottii
Dalea spinosa Darlingtonia californica
Darmera peltata Dasylirion longiformis
Dasylirion longissimum Dasylirion wheeleri
Datura stramonium Datura wrightii
Decumaria barbara Delphinium nudicaule
Delphinium nudicaule 'Laurin' Delphinium tricorne
Delphinium virescens Dendromecon rigida ssp. harfordii
Dennstaedtia punctilobula Dicentra cucullaria
Dicentra eximia Dicentra eximia 'Snowdrift'
Dicentra eximia 'Snowflakes' Dicentra formosa 'Adrian Bloom'
Dicentra formosa 'Bacchanal' Dicentra formosa 'Luxuriant'
Dichromena colorata Dichromena latifolia
Diervilla lonicera Diervilla rivularis 'Morton (Summer Stars™)'
Diervilla sessilifolia 'Butterfly' Diervilla x splendens
Dionaea muscipula