Robert Register Humphrey was born in 1904 in Palo Alto, Calif. He earned his bachelor's, master's and doctorate degrees in botany and geology from the University of Minnesota, graduating in 1933. He worked as a range ecologist with the U.S. Forest Service for 15 years, then as a range conservationist with the U.S. Soil Conservation Service before working for the University.
Humphrey joined the UA faculty as an associate professor in botany in 1948. He was involved in ecology, range management and was published extensively. His most notable book was "The Boojum and Its Home." He retired from the UA in 1966. After he retired, he and his wife traveled extensively in Mexico, Baja and California studying the boojum tree and ecology along the United States-Mexico border. A professor emeritus of range ecology at the University of Arizona, Humphrey died March 13, 2002, at 97.
The collection contains primarily photographs of grasses and other vegetation native to Arizona, New Mexico and Northern Mexico. It also includes photographs of boundary markers along the border between the United States and Mexico and some photographs of groups and individuals involved with Robert Humphrey in grasslands research.