Parthenium argentatum (guayule) and Taraxacum kok-saghyz (buckeye gold dandelion aka Russian dandelion, aka Kazak dandelion) are both being investigated and developed as supplements or replacements of imported natural rubber from Hevea brasiliensis (Brazilian or para rubber tree) in commercial applications. Guayule s best suited to the US southwest, and other semi-arid regions of the world, while buckeye gold is well suited to the northern United States, and regions with similar seasonal climates. The two species have faced, and face, similar and different challenges to commercialization including costs and efficiencies of agronomy, processing, rubber composition and product manufacture. Some of these will be discussed in relationship to each other and to the current primary source, Hevea brasiliensis. Presented by Katrina Cornish, Ph.D., FAAS Endowed Chair and Ohio Research Scholar, Bioemergent Materials, Departments of Horticulture and Crop Science, and of Food, Agricultural and Biological Engineering, The Ohio State University, Ohio Agricultural Research and Development Center.