- Earleaf Greenbrier
- Early Dog-violet
- Early Marsh-orchid
- Early meadow-rue
- Early Purple Orchid
- Eastern black nightshade
- Eastern black walnut
- Eastern Coral Bean
- Eastern Cottonwood
- Eastern gamagrass
- Eastern Groundsel
- Eastern hemlock
- Eastern Joshua tree
- Eastern pasqueflower
- Eastern poison ivy
- Eastern redbud
- Eastern redcedar
- Eastern shooting star
- Eastern Skunk Cabbage
- Eastern Teaberry
- Eastern Tree-mallow
- Eastern white pine
- Ebony spleenwort
- Eelgrass
- Eight-petal Mountain-Avens
- Elder-flowered Orchid
- Elecampane
- Elegant Clarkia
- Elegant Zinnia
- Elephant's Ear
- Elephant's-Head lousewort
- Elmleaf blackberry
- Emory's rockdaisy
- Enchanter's-nightshade
- Engelmann daisy
- Engelmann's Pricklypear
- English oak
- Eurasian baneberry
- European ash
- European aspen
- European barberry
- European beech
- European black elderberry
- European Cyclamen
- European dewberry
- European field pansy
- European Frog-bit
- European Globeflower
- European goldenrod
- European heliotrope
- European holly
- European Hornbeam
- European larch
- European lily of the valley
- European marram grass
- European mistletoe
- European mountain ash
- European Searocket
- European swallow-wort
- European water-horehound
- European Water-plantain
- European wood-sorrel
- European Woodland Sedge
- Evergreen Huckleberry
- Evergreen sumac