Bob is co-author of both the Shinners and Mahler's Illustrated Flora of North Central Texas and the upcoming Illustrated Flora of East Texas, as well as the Flora and Natural History of Gillespie County, Texas. In addition, Bob is collaborating with James B. Phipps of the University of Western Ontario to publish a field guide to the hawthorns (Crataegus, Rosaceae) of the world. He is, or has been, on the board of directors of several other organizations involved in landscape ecology and conservation, including the Natural Area Preservation Association (NAPA), the Native Prairie Association of Texas (NPAT), the Fort Worth Nature Center, the Dallas Nature Center, and the Useful Wild Plants of Texas project.
Besides maintaining an extensive database on the flora of Texas, Bob has carried out fieldwork in Africa, Antarctica, Asia, Australia, Canada, the Caribbean, Central and South America, and Mexico.
Bob is a retired senior Captain with American Airlines, where he piloted jets to Asia, Europe, the Caribbean, Central and South America, and throughout North America.