The lichen family Parmeliaceae belongs to order Lecanorales of the class Ascomycetes consisting of 85 genera 2,319 species The objectives of this study are to explore taxonomy of this family at Phu Hin Rongkla National Park. Fourteen genera (85species) were reported in Thailand This family is characterized by development of a foliose growth form. The symbiotic relationship between the algae
and the fungi forms in stratified layers Rhizinesusually present on the lower surface for attaching to substrata. Upper cortex is gray to green. The exciples,which support apothecia, are lecanorine types,
containing algae. The asci are filled with eight simple hyaline ascospores. Phycobionts are green algae,usually TrebouxiaThallus ornamentation andvegetative propagules as well as the medullary
substances are important characters useful for characterizing taxa.