Introduction to the Treatment of Pteridophytes

The following general remarks on the taxonomy of the pteridophytes at higher levels focus on the systematics of the ferns in a narrower sense, especially on what used to be called the leptosporangiates. The relationships between the classes of the traditional pteridophytes are still very difficult to assess, if indeed they are at all related in the sense of being derived from a common source of cormophytes. These relationships can only be discussed within a palaeobotanical framework (see p. 1), rather than in a work like the present, which concentrates on living plants.