Xanthoria parietina with Evernia prunastri
Xanthoria parietina is a foliose, or leafy, lichen. It has wide distribution, and many common names such as common orange lichen, yellow scale, maritime sunburst lichen and shore lichen. It can be found near the shore on rocks or walls (hence the epithet parietina meaning "on walls"), and also on inland rocks, walls, or tree bark. It was chosen as a model organism for genomic sequencing (planned in 2006) by the US Department of Energy Joint Genome Institute (JGI). In the past it was used as a remedy for jaundice because of its yellow color. The vegetative body of the lichen, the thallus, is foliose, and typically less than 8 centimetres (3.1 in) wide. The lobes of the thallus are 1–4 mm in diameter, and flattened down. The upper surface is some shade of yellow, orange, or greenish yellow, while the lower surface is white, with a cortex, and with sparse pale rhizines or hapters. The vegetative reproductive structures soredia and isidia are absent in this species, however, apothecia are usually present. The outer "skin" of the lichen, the cortex, is composed of closely packed fungal hyphae and serves to protect the thallus from water loss due to evaporation as well as harmful effects of high levels of irradiation. In Xanthoria parietina, the thickness of the thalli is known to vary depending on the habitat is which it grows. Thalli are much thinner in shady locations than in those exposed to full sunshine; this has the effect of protecting the algae that cannot tolerate high light intensities. The lichen pigment parietin gives this species a deep yellow or orange-red color.
Hardwood forests in low-elevation broad valleys; scattered on Populus and other hardwoods in riparian areas in agricultural and populated areas. It is often associated with high level of nitrogen and favored by eutrophication  and can be often found near farmland and around livestock. X. parietina is a widespread lichen, and has been reported from Australia, Africa, Asia, North America and throughout much of Europe. In eastern North America and Europe, it is found more frequently near coastal locations. The increases in NO3 deposition as a result of industrial and agricultural developments in southern Ontario, Canada in the 20th century are thought to be responsible for the reappearance of this species in the local lichen flora.
Evernia prunastri, also known as Oakmoss, is a species of lichen. It can be found in many mountainous temperate forests throughout the Northern Hemisphere, including parts of France, Portugal, Spain, North America, and much of Central Europe. Oakmoss grows primarily on the trunk and branches of oak trees, but is also commonly found on the bark of other deciduous trees and conifers such as fir and pine. The thalli of Oakmoss are short (3–4 cm in length) and bushy, and grow together on bark to form large clumps. Oakmoss thallus is flat and strap-like. They are also highly branched, resembling the form of deer antlers. The colour of Oakmoss ranges from green to a greenish-white when dry, and dark olive-green to yellow-green when wet. The texture of the thalli are rough when dry and rubbery when wet. It is used extensively in modern perfumery. Oakmoss is commercially harvested in countries of South-Central Europe and usually exported to the Grasse region of France where its fragrant compounds are extracted as Oakmoss absolutes and extracts. These raw materials are often used as perfume fixatives and form the base notes of many fragrances. They are also key components of Fougère and Chypre class perfumes. The lichen has a distinct and complex odor and can be described as woody, sharp and slightly sweet. Oakmoss growing on pines have a pronounced turpentine odor that is valued in certain perfume compositions.