Pteridophytes are the first terrestrial vascular plants (containing xylem and phloem) that reproduce via spores rather than seeds. Based on the nature of their leaf and stem vascular anatomy and the position of their sporangia, they are divided into four primary classes:

Psilopsida: The most primitive class, featuring photosynthetic stems and rhizoids instead of true roots (e.g., Psilotum).

Lycopsida: Commonly known as club mosses, they have well-differentiated plant bodies with true roots and microphyllous (small) leaves (e.g., Selaginella, Lycopodium).

Sphenopsida: Known as horsetails, characterized by jointed stems with whorls of scaly leaves at the nodes (e.g., Equisetum).

Pteropsida: Commonly known as true ferns, they have large leaves called fronds and are the most diverse group (e.g., Pteris, Dryopteris, Adiantum).

──────────────────────────────────────────────────────────────────────────────────────────