Flor received a Ph.D. degree in 1929 from the University of Minnesota. He worked for the USDA for three years at Washington State University and then for the remainder of his career at North Dakota State University. In the 1940s, Flor developed the gene-for-gene concept to explain the genetic interactions between Melampsora lini and flax. His theories were put to use in Flor’s own flax breeding program to successfully develop rust-resistant flax. This concept provided the underpinnings for research on the genetics of host-pathogen interactions for the next 70 years. Flor was elected a fellow of APS in 1965, received the Ruth Allen Award in 1966, was president of the society in 1967, and received the prestigious Award of Distinction in 1980.
(Submitted for publication in July 2008.)