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.