- Wagon Tree
- Wall barley
- Wall germander
- Wall Lettuce
- Wall Pennywort
- Wall Screw-moss
- Wall-rue
- Wallace's spikemoss
- Wand Mullein
- Warrior's Plume
- Warty-barked Spindle
- Warty-cabbage
- Water Avens
- Water caltrop
- Water Chickweed
- Water Fern
- Water forget-me-not
- Water hemlock
- Water horsetail
- Water Lettuce
- Water oak
- Water smartweed
- Watercress
- Watermint
- Waterpepper
- Watershield
- Waved Silk-moss
- Wavy-leafed soap plant
- Wavyleaf mullein
- Wavyleaf thistle
- Wax currant
- Wax myrtle
- Waxlip Orchid
- Wayfaring-tree
- Weld
- Welsh Poppy
- Welted Thistle
- Western blue flag
- Western blue-eyed grass
- Western Bunchberry
- Western coastal wattle
- Western columbine
- Western harebell
- Western hemlock
- Western horsenettle
- Western Ironweed
- Western Joshua Tree
- Western Lily of the Valley
- Western maidenhair fern
- Western poison ivy
- Western Ponderosa Pine
- Western prickly juniper
- Western ragweed
- Western Rattlesnake Plantain
- Western redcedar
- Western skunk cabbage
- Western Snowberry
- Western Soapberry
- Western Starflower
- Western stoneseed
- Western sword fern
- Western sycamore
- Western Wallflower
- Western white pine
- Western Wild Ginger
- Western yellow pond-lily
- Wheeler sotol
- Whipple's penstemon
- White ash
- White avens
- White baneberry
- White beggarticks
- White bog orchid
- White brodiaea
- White Bryony
- White Butterbur
- White campion
- White clover
- White deadnettle
- White fawnlily
- White fir
- White fringetree
- White Globe Lily
- White Hellebore
- White helleborine
- White Horehound
- White leadtree
- White meadowsweet
- White mulberry
- White Mullein
- White oak
- White pasqueflower
- White Point-vetch
- White poplar
- White ramping-fumitory
- White sage
- White snakeroot
- White spruce
- White stonecrop
- White Sweetclover
- White turtlehead
- White twisted-stalk
- White vervain
- White Wall-rocket
- White willow
- White Wood Aster
- White-flowered Rhododendron
- Whitebark Pine
- Whitemouth dayflower
- Whitesnow
- Whitetop sedge
- Whorled Clary
- Whorled loosestrife
- Whorled milkweed
- Whorled wood aster
- Wild Angelica
- Wild asparagus
- Wild Basil
- Wild bergamot
- Wild canterbury bells
- Wild carrot
- Wild cherry
- Wild clary
- Wild comfrey
- Wild Four o'Clock
- Wild garlic
- Wild geranium
- Wild hydrangea
- Wild Licorice
- Wild Liquorice
- Wild Madder
- Wild Mignonette
- Wild Pansy
- Wild parsnip
- Wild poinsettia
- Wild potato vine
- Wild quinine
- Wild radish
- Wild Rosemary
- Wild sarsaparilla
- Wild Service-tree
- Wild teasel
- Wild yam
- Willow gentian
- Willow oak
- Wineberry
- Winecup Clarkia
- Winecup mallow
- Winged euonymus
- Wingstem
- Winter Aconite
- Winterberry holly
- Winterfat
- Wishbone Bush
- Wood anemone
- Wood anemone
- Wood Avens
- Wood Club-rush
- Wood Cow-wheat
- Wood crane's-bill
- Wood Forget-me-not
- Wood horsetail
- Wood Lily
- Wood nettle
- Wood sanicle
- Wood spurge
- Wood Stitchwort
- Woodland germander
- Woodland pinedrops
- Woodland stonecrop
- Woodland strawberry
- Woods' rose
- Woolgrass
- Woolly Burdock
- Wormseed wallflower
- Wych Elm