The differentiation of spores into microspores and megaspores and their dependence on the parent sporophyte for the nutrition, are certain features in the life cycle of Selaginella, which have been considered as the essential pre-requisties for the formation of seeds, characteristic of spermatophytes. It is generally agreed, that the seed plants arose from the heterosporous vascular plants that instead of discharging the megaspore acquired the habit of retaining it within the megasporangium.