United States National Arboretum

Washington, D.C., United States

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The United States National Arboretum in Washington, D.C., established by Congress in 1927 and located on 446 acres along the Anacostia River, is a major botanical research and public garden operated by the U.S. Department of Agriculture. It features extensive themed collections such as azaleas, bonsai, camellias, hollies, apple trees, and slow-growing conifers, as well as the National Herb Garden and the National Grove of State Trees.

The arboretum houses the National Bonsai & Penjing Museum and displays iconic architectural elements like the 22 Corinthian National Capitol Columns from the U.S. Capitol. It serves both as a center for horticultural research and public education, attracting over half a million visitors per year.

The arboretum has significant historic value, listed in the National Register of Historic Places, and includes facilities like a botanical library and an herbarium with over 800,000 plant specimens. It plays a key role in plant conservation, development of ornamental plants, and botanical studies in the U.S..