The Washington Park Arboretum was designed by James Dawson of the Olmsted Brothers firm, and was developed in the 1930's with WPA funds and labor. Among the Arboretum's 20,000 trees, shrubs and vines, more than 10,000 are catalogued in collections. 4,600 different species are cultivated varieties from around the world, and 750 of the taxa were collected in the wild. 139 plants in the Washington Park Arboretum on the endangered species list. 95% of the Arboretum's collections are on display. Collections include rhododendron, azalea, mountain ash, pine, spruce, cedar, fir, crabapple, holly, magnolia, camellia, and Japanese maple.