A mixed breeding system involving the production of chasmogamous and cleistogamous flowers is common in most species of the genus Viola. This system can theoretically affect the patterns of reproduction and distribution of genetic variation in populations. While we understand the theoretical basis behind these expected patterns, there is little empirical evidence comparing the behavior of similar species in widely contrasting environments. To better characterize the effect that this breeding system has on reproduction and genetics a subtropical (Viola grahamii) and a temperate (V. striata) species of violets were compared. V. striata populations were studied in Ohio, USA, and V. grahamii in Michoacán, Mexico during 2002 and 2003. Weekly observations during the reproductive season allowed for the establishment of blooming patterns of the two flower types for each species. The allocation of resources towards flowering was evaluated under natural differential light availability and soil nutrients. The reproductive success of each of the flower types was determined and the genetic diversity in both species assessed.