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Xanthoria parietina: The Common Orange Lichen

Xanthoria parietina, a vibrant lichen, is known by several common names, reflecting its widespread presence and distinctive color.

Considerations for Pets

• This lichen can be found growing on rocks, concrete, and trees, even near cattle farms.

Considerations for Children

• Pigments from colorful lichens, including Xanthoria parietina, have been traditionally used to dye wool and other fibers.

Common Names

• Common orange lichen
• Yellow scale
• Maritime sunburst lichen
• Orange lichen
• Orange wall lichen
• Sunburst lichen
• Golden Shield Lichen
• Shore Lichen

Taxonomy and Nomenclature

• Scientific Name: Xanthoria parietina
• Genus: Xanthoria
• Family: Teloschistaceae
• It is also noted that the genus Caloplaca is in the family Teloschistaceae.

Distribution and Habitat

• Xanthoria parietina has a wide distribution and is found in various locations, including:
  • Rocks, concrete, and trees, particularly near cattle farms due to its preference for ammonia.
  • Areas near the coast.
  • On tombstones.
  • Humboldt Lagoons State Park, California.
  • Western Isles.
  • New Zealand, on coastal rocks as Xanthoria ligulata.

Morphological Characteristics and Growth Habits

• Xanthoria parietina is a foliose (leafy) lichen, forming large, rounded patches that can reach up to 10 cm across.
• It has wide, round-lipped marginal lobes.
• The thallus (body) color ranges from yellowish-green to golden-yellow or orange, and it may appear grey in shaded conditions.
• Fruiting structure has a dark orange disc that is surrounded by a lighter edge.

Ecological Role

• It can be especially prolific in certain environments, forming an orange lichen belt.

Interactions with Other Organisms

• Xanthoria elegans is highly tolerant of environmental conditions and grows in profusion in seabird areas due to tolerance.
• It forms a symbiotic relationship between a fungus and an alga.

Quirky Facts

• The orange color of this lichen is due to the production of the pigment parietin.
• Parietin, found in this lichen, may have potential as an anti-cancer drug.

Further Information

• Microchemical Methods for the Identification of Lichens by Alan Orange
• Lichens on Trees. A Guide to Some of the Commonest Species. Series: British Plant Life 3. National Museum of Wales. Orange, A. 1998.