The so-called `` seed ferns '' ( Pteridospermae ) were one of the earliest successful groups of land plants , and forests dominated by seed ferns were prevalent in the late Paleozoic .
The living spermatophytes form five groups : The fossil seed ferns ( Pteridospermatophyta ) were one of the earliest successful groups of land plants , and forests dominated by seed ferns were prevalent in the Permian .