Pteropsida (Filicopsida; ferns) Class of the Pteridophytina, which comprises all living and extinct ferns. They arose in the Devonian from the trimerophyte group of psilophytes (which had developed more elaborate systems of branching, that led on to the formation of true leaves) and made an important contribution to Carboniferous floras. They are the most advanced, numerous, and varied of the pteridophytes. In most cases they have relatively large, muchdivided leaves, and are still significant components of many different plant communities around the globe.

Pteropsida In older classifications, a subdivision of tracheophytes that contained the ferns and seed plants, or a class of the Pteridophyta containing only the ferns.