Northern & Central Midwest
The Widlflower Information Web site allows you to search for a specific wildflower by color, height, bloom time, region, and habitat, not to mention good old-fashioned scientific or common name. You can also sort by color, height, soil needs, sun needs, annual or perennial, or any other criteria you might need in order to plant a wildflower garden. There are usually at least two pictures accompanying the encyclopedia information, and the site also has impressive cultural information. This is an invaluable resource for the naturalistic or native garden.
If you purchase only one book to satisfy your need for a book on wildflowers, this is the one. Wildflowers (The New England Wild Flower Society), by William Cullina, is a beautiful book to begin with, beautiful enough for a coffee table display. The author is extremely knowledgeable, and his expertise comes from years at the New England Wildflower Society garden in Framingham, MA. Although the book is encyclopedic in scope, it is conversational in tone which makes it easily accessible and a pleasure just to sit down and read.