University of Texas - Austin. Lady Bird Johnson Wildflower Center.
Provides lists of native plants recommended for various purposes (by State or Canadian Province). Once you have selected a collection, you can browse the collection or search within it using the combination search. Also provides other special collections resources.
North American Native Plant Society.
Local Native Plant Societies are often your best source of information about plants native to your area.
Note: Provides information for State and Canadian Provinces.