The evolution of heterospory changed the conditions for spore dispersal. Assuming wind as the dispersal agent, microspores will be dispersed to greater distances than megaspores. We investigated aspects of spore size and sculpture as well as spore dispersal under calm con- ditions and under the effect of artificial wind of some Selaginella species. We found that differ- ences between the species existed that were correlated with active or passive release of micro- and megaspores. The dispersal efficacy changed drastically under the effect of wind, showing differences between the species. There was no support for the hypothesis of synaptospory between micro- and megaspores during active dispersal. Evidence suggests that active spore dispersal and wind may enhance outbreeding. More detailed investigations may reveal species specific corre- lations between life history traits, breeding systems, and spore dispersal. Heterospory and dioecy of gametophytes evolved independently in different clades of the pteridophytes. The separation of female megaspores and male microspores changed the conditions of spore dispersal. In homosporous, wind dispersed ferns the probability of being transported a certain distance is much the same for each spore. Assuming that in heterosporous pteridophytes wind dispersal is still dominant, the smaller and lighter microspores are likely to be dispersed to longer distances than the larger and heavier megaspores (Tryon and Lugardon, 1991). The dispersal distances of male and female gameto- phytes thus differ. Heterospory also affects the production of spores. Because of higher energetic investments, the number of megaspores per individual plant is reduced in comparison to the number of microspores (Tryon and Tryon, 1982). As a consequence, the dispersal ecology of heterosporous pte- ridophytes is likely to differ from that of homosporous ferns (Cousens, 1988). The heterosporous genus Selaginella P. Beauv. is widespread and contains numerous species (Jermy, 1990). The efficacy of their active spore dispersal mechanisms was first investigated by Goebel (1901). He showed that the mega- sporangium ejects the megaspores in a manner quite different from the micro-