Washington Park Arboretum photo by Peter Prehn on Flickr (noncommercial use permitted with attribution / no derivative works).
Official State Arboretum of Washington
Washington Park Arboretum was designated the official state arboretum of Washington in 1995. The Washington Park Arboretum (University of Washington Botanical Gardens near Seattle) is internationally recognized for its woody plant collections on 230 acres. All State Plants - All State Flowers
Washington State Arboretum Legislation
"The legislature finds that the arboreta in this state act as living museums devoted to the display and conservation of woody plant species from around the world that can grow in the Pacific Northwest. Arboreta enhance public appreciation for the aesthetic diversity of temperate woody plants; conserve both natural and cultivated woody plant taxa to preserve their diversity for future appreciation; educate the public and students concerning urban landscape use and the natural biology of temperate woody plants; and cooperate with similar institutions in this region and around the world in achieving these common goals. The legislature further finds that arboreta are of increasing importance as world biodiversity declines.
The Washington park arboretum is a two hundred acre living museum that is managed cooperatively by the city of Seattle and the University of Washington. It is devoted to the display and conservation of collections of plants from around the world which can grow in the Pacific Northwest. These plants are used for education, research, conservation, and a sense of public pleasure. The Washington park arboretum, the oldest center for botanical and gardening learning in the Pacific Northwest, is recognized as one of the two foremost collections of woody plants in the United States of America and enjoys an excellent international reputation. The legislature finds that it is fitting and appropriate to recognize the importance of the overall mission of the Washington park arboretum."