The maintenance of male plants and plants possessing both male and female reproductive organs in a single species has been termed androdioecy. However, several plant scientists have suggested that it is theoretically very difficult for this reproductive system to exist in nature. In fact, not one androdioecious species had been documented prior to current work. Dr. Rieseberg and his colleagues have recently demonstrated that the plant species Datisca glomerata is androdioecious and propose the determine how this reproductive system originated and how it is being maintained. Because Datisca glomerata is the only plant species known to be androdioecious, it will provide a model system for studies in the field of plant biology. Basic scientific questions can be addressed using this model system: 1) how do different reproductive systems in plants evolve and how are they maintained? 2) how can one reproductive system be changed to another? and 3) what is the genetic or environmental basis for this change? These questions are important for basic plant ecologists, but are also relevant to breeders trying to improve existing crop plants or trying to develop new agriculturally important plants. For example, a species that has both male and female plants is quite inefficient as a crop plant because only 50% of the plants will bear fruit. Understanding reproductive system evolution is also important for the maintenance of biodiversity. Changes in reproductive system can alter species stability and potentially lead to their extinction.