Glossary - Progymnosperm
Extinct group of plants that existed during the Devonian and Carboniferous. The Progymnosperms had a secondary growth similar to Gymnosperms but reproduced with the help of spores, like ferns. Archaeopteris was an arborescent Progymnosperm.
Some Progymnosperms were heterosporous: they produced two different types of spores. It is possible that this group is the ancestor of, or a close relative to, Angiosperms.
