Illinois Dewberry
Illinois Greenbrier
Illinois Hawthorn
Illinois Pondweed
Illinois Ticktrefoil
Indian Blanket
Indian Cucumber
Indian Goosegrass
Indian Lovegrass
Indian Mallow
Indian Paintbrush
Indian Plantain
Indian Strawberry
Indian Woodoats
Indian-tobacco
Indiangrass
Indianhemp
Indianpipe
Inflated Narrow-leaf Sedge
Inland Bluegrass
Inland Sedge
Intermediate Mermaidweed
Intermediate Woodfern
Interrupted Fern
Introduced Sage
Inundated Clubmoss
Iowa Moonwort
Ipomopsis
Iris
Irish Potato
Ironweed
Italian Bugloss
Italian Ryegrass
Italian Woodbine
Ithaca Blackberry
Ivy
Ivyleaf Morning-glory