Botanique (listing of more than 2700 gardens, arboreta, and nature sites)
Smithsonian Horticulture Services
University of Washington Botanic Gardens
The United States National Arboretum Gardens and Horticulture
Fairchild Tropical Botanic Garden
Bowdoin College Japanese Gardens in Maine
Royal Botanic Garden Edinburgh
Ethel M. Chocolates and Cactus Garden
Red Butte Gardens and Arboretum