Pteridospermatophyta, also called seed ferns, is an extinct spermatophyte group of the Plantaekingdom. Members of this division were predominant at the late Devonian, declined some 250 million years ago, and mostly disappeared by the Cretaceous, though fossil evidence indicates that they survived into the Eocene in Tasmania.[1] The Pteridospermatophyta have not yet acquired a clear position in botanical systematics and indeed appear to be a paraphyleticform taxon. Some appear to be allied or ancestral to the gymnosperms, others seem to be closer to angiosperms.
The seeds of seed ferns develop differently from the other seed plants, as they are believed to grow inside a cupule.
^ McLoughlin, S., R.J. Carpenter, G.J. Jordan, & R.S. Hill. (2008). "Seed ferns survived the end-Cretaceous mass extinction in Tasmania." American Journal of Botany,95: 465-471.
