The Morton Arboretum, in Lisle, Illinois, is a public garden and outdoor museum with a library, herbarium, and program in tree research including the Center for Tree Science. Its grounds, covering 1,700 acres (6.9 Square kilometres), include cataloged collections of trees and other living plants, gardens, and restored areas, among which is a restored tallgrass prairie. The living collections include more than 4,100 different plant species, which can be referenced in an online database.