Here are my contributions for this week's task, John. This was a brain teaser and as you can tell it took me a while to search my files to get a good cross-section of the United States.
Midwest: Large Flowering Trillium IL.
West Coast Rain Forest. Hoh Rain Forest, WA.
California: Redwood Forest
California: Cholla Cactii, Phacelia, Brittlebush, Lupine, and Brown-eyed Primrose in the Mojave Desert
Alpine Habitat: Bear Grass and Heather, Mt. Rainier, WA
Hawaii Desert: Silversword plants on Haleakala Volcano, HI
New England: Birches and Sugar Maples, NH
Tropical climate: Kalalau Valley, Kokee State Park, Hawaii