- cinnamon
- cirriferous
- cirrus
- clavate
- claviform
- chlorophyll
- cinqfoil
- chrysanthemum
- cicatrice
- cinquefoil
- circinate
- cirri
- citron
- citrus
- circumnutation
- citronella
- cleistogamic
- clematis
- climb
- clone
- clove
- clover
- club-moss
- coat
- cob
- climber
- coca
- cockscomb
- coco
- coco-palm
- cocoa
- coconut-palm
- coconut-tree
- codger
- colollaceous
- colony
- cole-seed
- colza
- coma
- comae
- comb-out
- conduplicate
- comose
- composite
- conifer
- coniferous
- cone
- constituency
- convolute
- coquito
- coralline
- convallaria
- coreopsis
- corm
- cornaceous
- cornel
- coronate
- coronated
- corozo
- couch-grass
- cowslip
- corymb
- cosmos
- cotyledon
- crassulaceous
- cranberry
- crenate
- crenated
- cress
- crocus
- cruciferous
- cryptogam
- cryptogamous
- cuckoo-pint
- cucumber
- cucurbit
- cummin
- curvinervate
- cusp
- custard-apple
- cuticle
- cryptogamic
- cucurbitaceous
- cumin
- cumquat
- cup
- cupule
- curcuma
- cycad
- cyclamen
- cyme
- cypress
- daffadowndilly
- daffodil
- daffodilly
- dahlia
- daisy
- decanadrous
- dehisce
- dehiscence