All Fern and Clubmoss Classes

The ferns are an ancient lineage dating back to at least the Devonian, with three living groups, the Marattiales, the Ophioglossales and the leptosporangiate ferns, plus a couple of extinct groups. The Psilotales are tentatively included with them, although they differ so much from living ferns that their relationships are uncertain. The club mosses and their relatives, the lycophytes, are a separate group, the oldest extant group of vascular plants. In the Carboniferous some lycophytes were forest-forming trees more than 35 meters tall, and their leaves are microphylls with a single unbranched vein.