Bouteloua chondrosioides (Poaceae) is a prennial, gynodioecious, Chloridoid grass with both diploid (2N=20) and polyploid (2n=40; 80) populations that vary in levels of male sterility. B. chondrosioides was initially considered to be hermaphroditic; however Reeder and Reeder in 1966 described a male sterile form that makes aborted anthers (MA form) not visible to the naked eye. This form has been observed in all populations surveyed to date. A second, independently segregating form of male sterility has also been recently identified. This form makes stamens of reduced size that contain no pollen grains (MS form). Both forms have been found in all Texas and Arizona populations observed. No correlation between ploidy levels and levels of male sterility has been observed. In this talk I will outline evidence from work performed to date supporting the hypothesis that the transmission of male sterility in the gyndioecious Bouteloua chondrosioides appears to be primarily determined by cytoplasmic male sterility.

Key words: Bouteloua, gynodioecy