Cheilanthes

Cheilanthes (lip ferns) is a genus of about 180 species of rock-dwelling ferns with a cosmopolitan distribution in warm, dry, rocky regions, often growing in small crevices high up on cliffs. Most are small, sturdy and evergreen. The leaves, often densely covered in trichomes, spring directly from the rootstocks. Many of them are desert ferns, curling up during dry times and reviving with the coming of moisture. At the ends of veins sporangia, or spore-bearing structures, are protected by leaf margins, which curl over them.
Taxonomy.
The genus name is derived from the Greek words χεῖλος ("cheilos"), meaning "lip," and ἄνθος ("anthos"), meaning "flower."
"Cheilanthes" as traditionally circumscribed is now known to be highly paraphyletic, comprising at least four generically separate groups. The type species, "C. micropteris", is most closely allied to the genera "Aleuritopteris" and "Sinopteris" (Schuettpelz "et al."). In the early 21st century, many species, principally from the New World, were moved into the new genus "Gaga" and the revived genus "Myriopteris". Further work remains to be done to render "Cheilanthes" monophyletic. Members of many other cheilanthoid genera have at times been given names in the genus.
Species.
The circumscription of the genus was uncertain . The "Checklist of Ferns and Lycophytes of the World" lists species in several distinct groups.
"Cheilanthes" sensu stricto contains about 20 species from North and tropical Central and South America:
"Cheilanthes" sensu lato contains about 50 species that molecular phylogenetic studies suggest do not form a clade with the core "Cheilanthes" species, falling into separate clades, but for which no placement outside "Cheilanthes" was available :