Parmeliaceae

The Parmeliaceae is a large and diverse family of Lecanoromycetes. With over 2700 species in 71 genera, it is the largest family of lichen-forming fungi. The most speciose genera in the family are the well-known groups: Xanthoparmelia (822 species), Usnea (355 species), Parmotrema (255 species), and Hypotrachyna (262 species). Nearly all members of the family have a symbiotic association with a green alga (most often Trebouxia spp., but Asterochloris spp. are known to associate with some species). The majority of Parmeliaceae species have a foliose, fruticose, or subfruticose growth form. The morphological diversity and complexity exhibited by this group is enormous, and many specimens are exceedingly difficult to identify down to the species level. The family has a cosmopolitan distribution, and is present in a wide range of habitats and climatic regions. This includes everywhere from roadside pavement to alpine rocks, from tropical rainforest trees to subshrubs in the Arctic tundra......read more on Wikipedia.