- Fall phlox
- False Daisy
- False indigo bush
- False London-rocket
- False nettle
- False rue anemone
- False Sarsaparilla
- False staghorn fern
- False sunflower
- False yellowhead
- Fan clubmoss
- Felt Paintbrush
- Fennel
- Fetterbush lyonia
- Feverfew
- Field bindweed
- Field chickweed
- Field Cow-wheat
- Field Elm
- Field Eryngo
- Field forget-me-not
- Field horsetail
- Field madder
- Field maple
- Field marigold
- Field penny-cress
- Field peppergrass
- Field Scabious
- Field thistle
- Field woodrush
- Finger Grass
- Fingered Sedge
- Fire cherry
- Fire pink
- Firebush
- Firecrackerbush
- Fireweed
- Firewheel
- Fishbone Fern
- Five-bladed motherwort
- Flamboyant
- Flat-branched tree-clubmoss
- Flat-leaved Scalewort
- Flat-top white aster
- Flat-topped goldenrod
- Flattened Rush
- Flax-leaved Daphne
- Flax-leaved Horseweed
- Flixweed
- Floating marsh pennywort
- Floating primrose-willow
- Floating-leaved pondweed
- Flower-of-an-hour
- Flowering dogwood
- Flowering spurge
- Flowering-rush
- Fluttering Elm
- Fly Honeysuckle
- Foothill desert-parsley
- Forking Larkspur
- Fortune's spindle
- Fountain Grass
- Fourleaf manyseed
- Fourwing Saltbush
- Foxglove beardtongue
- Foxtail Barley
- Fragrant bedstraw
- Fragrant Orchid
- Fragrant sumac
- Frémont Cottonwood
- Fremont's Death Camas
- French broom
- Fringe cups
- Fringe Myrtle
- Fringed loosestrife
- Fringed polygala
- Fringed sagebrush
- Fringed willowherb
- Frog Orchid
- Frost aster
- Frostweed
- Fuchsiaflower Gooseberry