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. 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. Members of the Parmeliaceae are found in most terrestrial environments. Several Parmeliaceae species have been assessed for the global IUCN Red List. Read more on Wikipedia.