In 1963, the International Association of Botanic Gardens defined a botanic garden as a garden “open to the public in which the plants are labeled.” There are nine in the top 20, from first-place finisher Boyce Thompson Arboretum in Arizona to both members of the last-place tie: Illinois’s Chicago Botanic Garden and Florida’s Fairchild Tropical Botanic Garden. Australia has three entries in the top 20—Melbourne’s Royal Botanic Gardens, Sydney’s Royal Botanic Gardens, and the Adelaide Botanic Garden—and Wales has two.