Ellsworth Paine Killip, botanist, was born in Rochester, New York, on September 2, 1890. Killip attended the University of Rochester and received an A.B. in 1911. From 1914 to 1917, Killip held the position of associate curator at the Rochester Academy of Sciences.
On July 7, 1919, Killip was appointed as an aid in the United States National Museum, Division of Plants. He became assistant curator of the Division in December 1927, and on June 1, 1928, became an associate curator. Upon the retirement of William Ralph Maxon in 1946, Killip was made curator of the Division of Plants. During Killip's administration, the Division of Plants underwent reorganization. The Division was separated from the Department of Biology and raised to the status of a department, becoming the Department of Botany on July 31, 1947. Killip became head curator of the Department and also held the title of acting curator for the Division of Cryptogams, one of four original divisions formed under the reorganization. Killip retained both titles until his retirement from the Department in 1950. From 1951 through 1965, Killip continued his research and his ties with the USNM as a research associate in the Division of Phanerogams.
Killip's main studies were on the taxonomy of South American plants. Some of his expeditions to South America are documented in this collection. Among his publications is an article, "American species of Passifloraceae," 1938, and a major study on the passionflower family that was published in two volumes.
Killip was a member of the American Association for the Advancement of Science, the Cosmos Club, and the Washington Biologists' Field Club. He died in California on November 28, 1968.