Cy
- Cycloloma — pigweeds
- Cycloloma atriplicifolium — winged pigweed
- Cynoglossum — comfreys
- Cynoglossum boreale — northern wild comfrey
- Cyperus — flatsedges
- Cyperus bipartitus — river cyperus, shining flatsedge
- Cyperus dentatus — toothed umbrella-sedge
- Cyperus diandrus — umbrella sedge
- Cyperus erythrorhizos — redroot flatsedge
- Cyperus esculentus — yellow nutgrass, yellow umbrella sedge, chufa flatsedge
- Cyperus flavescens — yellow cyperus
- Cyperus houghtonii — Houghton's flatsedge, Houghton's cyperus
- Cyperus lupulinus subsp. macilentus
- Cyperus odoratus — rusty flatsedge
- Cyperus schweinitzii — Schweinitz' umbrella sedge, Schweinitz' flatsedge
- Cyperus squarrosus — awned cyperus
- Cyperus strigosus — straw-coloured flatsedge
- Cypripedium — lady's-slippers
- Cypripedium acaule — pink lady's-slipper, pink moccasin flower
- Cypripedium arietinum — ram's-head lady's-slipper
- Cypripedium candidum — small white lady's-slipper Endangered
- Cypripedium parviflorum var. makasin — northern small-flowered yellow lady's-slipper
- Cypripedium parviflorum var. pubescens — large yellow lady's-slipper, yellow moccasin flower, flat-petalled yellow lady's-slipper, golden slipper, whip-poor-will's shoe
- Cypripedium passerinum — sparrow's-egg lady's-slipper, Franklin's lady's-slipper
- Cypripedium reginae — showy lady's-slipper, queen lady's-slipper
- Cystopteris —
- Cystopteris bulbifera — bulblet bladder fern
- Cystopteris fragilis — fragile fern, brittle bladder fern
- Cystopteris laurentiana — Laurentian bladder fern, Laurentian fragile fern
- Cystopteris montana — mountain bladder fern
- Cystopteris protrusa — lowland brittle fern
- Cystopteris tenuis — MacKay's brittle fern
Read more about this topic: List Of Canadian Plants By Genus C