Establishment of a National Botanical Garden : hearing before a Joint Committee on the Library, Congress of the United States, Sixty-sixth Congress, second session, on S. 497, a bill to increase the area of the United States Botanic Garden in the City of Washington, District of Columbia and S. Res. 165, directing the Committee on the District of Columbia to report plans for the creation in or near the District of Columbia of a botanic garden comparable with the best existing gardens