In this website, a total number of 2022 species from 40 families are listed. The fern and fern allies checklist is divided into three parts:
Part 1. Aspleniaceae to Gleicheniaceae
Part 2. Hymenophyllaceae to Polypodiaceae
Part 3. Psilotaceae to Thelyptericaceae
Hassler, Michael (2004 – 2021): World Ferns. Synonymic Checklist and Distribution of Ferns and Lycophytes of the World. Version 12.3; last update May 28th, 2021. – www.worldplants.de/ferns/. Last accessed 27 June 2021.