The plant physiologist and historian Rodney H. True (1866-1940) divided his career relatively evenly between the Bureau of Plant Industry in United States Department of Agriculture and the Department of Botany and Morris Arboretum of the University of Pennsylvania. A specialist in the physiological function of mineral nutrients in plants, True was active in his later career in the Philadelphia Society for Promoting Agriculture, the Pennsylvania Horticulture Society, and the Agricultural History Society. The True Papers consist of 6 linear feet of material relating primarily to the period of his career spent at the University of Pennsylvania. The collection contains roughly equal proportions of personal and professional correspondence, with a few diaries and research notebooks documenting his involvement with professional organizations and his interests in the history of his discipline.