Clade of woody plants intermediate between ferns and gymnosperms comprising the Devonian genus Archaeopteris. Like the true gymnosperms, they commonly had secondary growth of their vascular tissues (i.e. they produced wood), and some grew to be tall trees. However, unlike true gymnosperms, they did not produce seeds, but rather released their spores as do ferns. Two major groups of progymnosperms are recognized, the Archaeopteridales and Aneurophytales. A third group, the Protopityales is sometimes recognized, but it is poorly known, and so its relationship to other plants is unclear.
