Ca
- Cakile — searockets
- Cakile edentula — American searocket
- Calamagrostis — reedgrasses
- Calamagrostis canadensis — Canada bluejoint, Canada reedgrass, Langsdorff's reedgrass, Macoun's reedgrass
- Calamagrostis deschampsioides — circumpolar reedgrass
- Calamagrostis lapponica — Lapland reedgrass
- Calamagrostis purpurascens — purple reedgrass
- Calamagrostis stricta subsp. inexpansa — bog reedgrass, northern reedgrass
- Calamintha — calamints
- Calamintha arkansana — low calamint, savoury, wild calamint, limestone wild basil
- Calamovilfa — sandreeds
- Calamovilfa longifolia var. magna — prairie sandreed
- Calla — callas
- Calla palustris — wild calla, water arum
- Callitriche — water-starworts
- Callitriche hermaphroditica — narrowleaf water-starwort, northern water-starwort, autumnal water-starwort
- Callitriche heterophylla — larger water-starwort
- Callitriche palustris — vernal water-starwort
- Callitropsis —
- Callitropsis nootkatensis — Alaska yellow cedar, Nootka false-cypress, yellow cedar
- Calopogon — grass-pinks
- Calopogon tuberosus — tuberous grass-pink
- Caltha — marsh marigolds
- Caltha natans — floating marsh marigold
- Caltha palustris — marsh marigold, cowslip, kingcup, cowflock
- Calypso — calypsoes
- Calypso bulbosa — calypso, fairy-slipper, nymph-of-the-north
- Calystegia — bindweeds
- Calystegia sepium — hedge bindweed, wild morning glory
- Calystegia spithamaea — low bindweed
- Camassia — hyacinths
- Camassia scilloides — wild hyacinth Threatened
- Campanula — bellflowers
- Campanula aparinoides — marsh bellflower, bedstraw bedflower, marsh harebell
- Campanula rotundifolia — American harebell, Scottish bluebell, bluebells of Scotland
- Campanulastrum — bellflowers
- Campanulastrum americanum — tall bellflower, American bellflower
- Campsis — trumpet vines
- Campsis radicans — trumpet vine, trumpet creeper
- Canadanthus —
- Canadanthus modestus — Canada aster, western bog aster, great northern aster, purple northern aster
- Cardamine — toothworts
- Cardamine bulbosa — spring cress, bulbous cress
- Cardamine concatenata — cutleaf toothwort, five-parted toothwort, slender toothwort
- Cardamine diphylla — twoleaf toothwort, broadleaf toothwort, crinkleroot
- Cardamine douglasii — purple cress, limestone bittercress
- Cardamine parviflora — small-flowered bittercress, sand bittercress
- Cardamine pensylvanica — Pennsylvania bittercress, Quaker bittercress
- Cardamine pratensis var. angustifolia — meadow bittercress
- Cardamine pratensis var. palustris — cuckoo-flower, lady's smock
- Carex spp.
- see List of Carex species in Canada
- Carpinus — hornbeams
- Carpinus caroliniana — ironwood, American hornbeam, blue beech, musclewood
- Carya — hickories
- Carya cordiformis — bitternut hickory, swamp hickory, pignut hickory, yellowbud hickory
- Carya glabra — pignut hickory, sweet pignut, red hickory
- Carya laciniosa — big shellbark hickory
- Carya ovata — shagbark hickory, upland hickory, shellbark hickory
- Castanea — chestnuts
- Castanea dentata — American chestnut, toothed chestnut Endangered
- Castilleja — Indian paintbrushes
- Castilleja coccinea — scarlet Indian paintbrush, scarlet painted-cup
- Castilleja raupii — Raup's painted-cup, Raup's Indian paintbrush
- Castilleja septentrionalis — northern paintbrush, Labrador Indian paintbrush
- Catabrosa — brook grasses
- Catabrosa aquatica — brook grass, water hairgrass
- Caulophyllum — cohoshes
- Caulophyllum giganteum
- Caulophyllum thalictroides — blue cohosh
Read more about this topic: List Of Canadian Plants By Genus C