SafePlants

Xanthoria parietina: Common Orange Lichen and More

Xanthoria parietina, a member of the Teloschistaceae family, is a foliose (leafy) lichen known by several common names, reflecting its vibrant color and habitat.

Considerations for Pets

• This lichen grows on rocks, concrete, and trees, sometimes near cattle farms. While the text does not explicitly state toxicity, be mindful of potential ingestion by pets, especially if the lichen is growing in areas with potential exposure to fertilizers, pesticides, or other environmental contaminants.

Considerations for Children

• The pigment parietin can be extracted from this and other colorful lichens by boiling for the purpose of dyeing wool or other fibers.

Nomenclature and Taxonomy

• Scientific Name: Xanthoria parietina
• Family: Teloschistaceae
• Genus: Xanthoria
• Common Names: Common orange lichen, yellow scale, maritime sunburst lichen, orange lichen, orange wall lichen, golden shield lichen, shore lichen.

Distribution and Habitat

• Xanthoria parietina has a wide distribution, appearing on rocks, concrete, and trees.
• It's often found in coastal areas and even mountainous regions, growing on exposed rocks and sometimes near cattle farms where ammonia levels are higher.
• Specific mentions include the Western Isles, New Zealand (coastal rocks), Humboldt Lagoons State Park, California and Yellowstone National Park, Wyoming.

Morphology and Growth

• It is a foliose lichen, forming large, rounded patches that can reach up to 10 cm in diameter.
• The thallus (body) is yellowish-green to orange, sometimes appearing grey in shaded conditions.
• It features wide, round-lipped marginal lobes and usually has apothecia (fruiting bodies) present.

Quirky Facts

• The color of Xanthoria parietina can vary depending on the amount of sun or rain exposure. Lichens in shade may appear green, while those in full sun are more intensely orange or yellow.
• Orange lichens can sometimes identify hunting perches of birds and grow prolifically in seabird colonies.

Ecological Role

• Xanthoria parietina can grow on rough, water-retentive, naturally alkaline bark.
• It can be found below the White and Grey lichen zones, forming an orange lichen belt.

Interactions with Other Organisms

• Lichens, including Xanthoria parietina, are described as "dual organisms" due to their symbiotic relationship between a fungus and an alga. The alga is contained within the hyphae of the fungus.

Potential Uses

• The orange pigment, parietin, is responsible for the lichen's color.
• Parietin is found not only in lichens but also in rhubarb.
• There is potential research into parietin as an anti-cancer drug due to its interference with certain biological processes.

Further Information

• Microchemical Methods for the Identification of Lichens by Alan Orange
• Tony Rebelo's reputation in Fungi and Lichens