Fissidens

Fissidens is an acrocarpous genus characterized by the presence of vaginal lamina on their leaves, which may be palmately or pinnately arranged. Each leaf consists of one dorsal lamina, which is the farthest away from the central strand, and two vaginal lamina which clasp the central strand. They are connected via a single costa, though this costa is infrequently nearly absent. ==Subordinate taxa==

Fissidens is generally accepted to include multiple subgenera, though these are disputed from publication to publication. A 2004 publication on the infrageneric taxonomy included four: Aloma, Fissidens, Octodiceras, and Pachyfissidens. In 2018, the clade Fissidens was confirmed to be monophyletic and only three subgenera were recognized: Fissidens, Pachyfissidens, and the novel Neoamblyothallia. Subsequent analysis of these clades found that the subgenera Aloma and Octodiceras as described by Pursell and Bruggeman-Nannenga in 2004, were strongly indicated to be monophyletic. Three sections described in 2018 were also indicated to be monophyletic, but none of the subgenera were. This 2022 infrageneric analysis determined that all other subgenera and sections were nonmonophyletic. ==Included species==