Robert Anthony DeFilipps, 65, an internationally renowned botanist at the Smithsonian Institution's National Museum of Natural History, died July 4 of heart disease at Washington Hospital Center. He lived in the District.

Dr. DeFilipps, who had worked at the Smithsonian since 1974, wrote six books and dozens of articles about endangered species, tropical plants and ornamental gardening. His scientific specialty was floristics, the study of the distribution and relationships of plant species in a particular area. He traveled around the globe for his research and provided the first scientific descriptions of 14 species of flowering plants.

One of his most renowned works, "Endangered and Threatened Plants of the United States" (1978), came about when Congress, under the mandate of the Endangered Species Act of 1973, asked the Smithsonian to compile a list of the nation's plants threatened with extinction. By reviewing material from botanists and other experts across the country and analyzing historical specimens in the Smithsonian's collections, Dr. DeFilipps created the nation's first comprehensive catalogue of endangered plants.

Among his other publications, some written with co-authors, were "Medicinal Plants of India" (1991), "Ornamental Garden Plants of the Guianas" (1992) and "A Checklist of the Trees, Shrubs, Herbs and Climbers of Myanmar" (2003). He owned a house on the Caribbean island of Dominica and in 1998 published "Useful Plants of the Commonwealth of Dominica, West Indies."

He also wrote an extensive paper on plants used in Haitian voodoo religious ceremonies. At the time of his death, he had compiled 1,000 pages of a dictionary of the plants of Haiti.

Dr. DeFilipps was born in Chicago and graduated from the University of Illinois. He received master's and doctoral degrees in botany from Southern Illinois University. He spent five years as a research associate at the University of Reading in England before joining the Smithsonian.

His hobbies included building tropical ornamental gardens, using native species, in Dominica, Fiji, India and Haiti.

Survivors include a brother.