Illinois Bundleflower
Illinois Greenbrier
Illinois Horse-gentian
Illinois Pinweed
Illinois Pondweed
Illinois Ticktrefoil
Indian Blanket
Indian Breadroot
Indian Goosegrass
Indian Lovegrass
Indian Mallow
Indian Paintbrush
Indian Plantain
Indian Strawberry
Indian Woodoats
Indian-tobacco
Indiangrass
Indianhemp
Indianpipe
Inflated Narrow-leaf Sedge
Inland Muhly
Inland Rush
Inland Sedge
Interior Ironweed
Intermediate Wheatgrass
Intermediate Woodfern
Interrupted Fern
Inundated Clubmoss
Iodanthus
Iowa Barley
Iowa Golden Saxifrage
Iowa Moonwort
Ipomopsis
Iris
Ironweed
Italian Bugloss
Italian Ryegrass
Ithaca Blackberry
Ivyleaf Morning-glory