Between 1986 and 1990 a collection of vascular plants from several natural areas of National Park Service lands in the District of Columbia was conducted. These voucher specimens are deposited in the United States National Herbarium (US) at the Smithsonian Institution. Sixty-six species are new reports for the District of Columbia. They represent 33 families and 54 genera. Ten are indigenous species and 56 are introduced.
The project described in this paper is the outcome of National Park Service cooperation with the Smithsonian Institution and The Nature Conservancy. The purpose is to provide a checklist of vascular plants in the District of Columbia at the end of the twentieth century. Since the District of Columbia is not a state it has been excluded or inadequately represented in published state and county plant lists.