Class Psilotatae is a small, ancient group of ferns characterized by their simplicity. These ferns lack true leaves, stems, and roots, and they reproduce by spores rather than seeds. There are several synonyms for this class of ferns, including Psilopsida, Psilophyta, and Psilotopsida. These names all refer to the same group of ferns and are used interchangeably depending on the classification system being used. Despite their simple morphology, these ferns have a fascinating evolutionary history and are an important component of many ecosystems around the world.