Pteridophyte spores, the main agent of dispersal carrying the essential genet ic material for sexual reproduction of plants and persistence of the species, are single, airborne cells with complex walls. Palynological records of these spores supply stratigraphic data and evidence of early diversification of vas cular plants, as well as testimony of climatic and vegetational changes. Compared to the extensive work on pollen, there are relatively few mod ern studies on development and structure of pteridophyte spore walls. This survey provides a source of original information on these spores,...