Widespread abortion of sporophytes in the desert moss Grimmia orbicularis occurred following unusually heavy summer rainstorms in the Mojave Desert of southern Nevada. Approximately 50% of the sporophyte cohort aborted, the majority in the seta elongation phenophase. Just prior to the abortions, an August rain event equivalent to one-half of the normal annual precipitation occurred over a period of less than six hours. Abortive sporophytes were significantly shorter and had significantly less biomass than viable mature sporophytes from the same cohort. A phenological and length analysis of the sporophyte cohort indicates that the sporophyte abortions occurred over a very brief period of time. It is postulated that the stresses brought on by desiccation/rehydration cycles during the summer heat in the desert, in conjunction with the presence of an abnormally advanced phenophase (early seta elongation), may have resulted in an inability to either repair the cellular damage or resulted in insufficient nutrients for sporophyte maturation.