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Xanthoria parietina: Common Orange Lichen

Xanthoria parietina, a foliose (leafy) lichen, is known by several common names, including common orange lichen, yellow scale, maritime sunburst lichen, orange lichen, and orange wall lichen.

Taxonomy and Nomenclature

• Scientific Name: Xanthoria parietina
• Family: Teloschistaceae
• Genus: Xanthoria

Distribution and Habitat

• Xanthoria parietina has a wide distribution and is often found on rocks, concrete, and trees.
• It can be found near cattle farms, as it favors environments with ammonia.
• It is also found in coastal areas, such as the coasts of New Zealand.
• It can be found in various regions, including the Western Isles, Yellowstone National Park (Wyoming), and Humboldt Lagoons State Park (California).

Morphological Characteristics

• It is a foliose lichen that forms large, rounded patches, up to 10 cm across.
• It features wide, round-lipped marginal lobes.
• The thallus (body) is typically yellowish-green to golden-yellow or orange, but can appear grey in shaded areas.
• The fruiting structure has a dark orange disc surrounded by a lighter edge.

Ecological Role

• Orange lichens can identify hunting perches of birds and grow prolifically in seabird colonies.
• The color of lichens can vary based on environmental conditions such as sun exposure and rainfall; for example, orange or yellow lichens in shade may appear green.

Interactions with Other Organisms

• Lichens are a symbiotic association between a fungus and an alga. The alga resides within the hyphae of the fungus.

Quirky Facts

• The orange color is due to the production of the pigment parietin.
• Lichens have been described as "dual organisms" because of their symbiotic nature.

Further Information

• Microchemical Methods for the Identification of Lichens by Alan Orange is noted as a guide.