SafePlants

Xanthoria parietina: The Common Orange Lichen

Xanthoria parietina is a striking foliose lichen known for its vibrant colors and wide distribution. Often referred to as the common orange lichen, it's a fascinating example of a symbiotic relationship in the natural world.

Considerations for Pets

• Lichens, including Xanthoria parietina, can grow on rocks, concrete, and trees, sometimes near cattle farms or other areas where animals might encounter them.

Considerations for Children

• The bright colors of Xanthoria parietina, such as its orange or yellow hue, might attract the attention of children.
• Lichens often grow on rocks and tombstones, which may be accessible to children in outdoor environments.

Taxonomy and Nomenclature

• Scientific Name: Xanthoria parietina
• Common Names: Common orange lichen, yellow scale, maritime sunburst lichen, orange lichen, orange wall lichen, golden shield lichen, shore lichen.
• Genus: Xanthoria (a genus of lichenized fungi)
• Family: Teloschistaceae

Distribution and Habitat

• Xanthoria parietina has a wide distribution and can be found in various locations.
• It commonly grows on rocks, concrete, trees, and tombstones.
• It is often found near coastlines.
• It can also be found in mountainous regions and even the desert.
• Specific locations mentioned include the Western Isles, New Zealand coastal rocks, Humboldt Lagoons State Park in California, and Mount Washburn Trail in Yellowstone National Park, Wyoming.

Morphological Characteristics

• It is a foliose (leafy) lichen.
• It forms large, rounded patches that can grow up to 10 cm across.
• The thallus (body) ranges from yellowish-green to golden-yellow or orange, but can appear grey in shaded conditions.
• It lacks isidia or soredia.
• Apothecia (fruiting bodies) are usually present.
• The fruiting structure has a dark orange disc surrounded by a lighter edge.

Ecological Role

• This lichen is often prolific and can form an orange belt on rocks.
• It favors environments rich in ammonia, such as areas near cattle farms.
• It is highly tolerant of environments affected by seabirds.
• It is known to grow on rough, water-retentive, naturally alkaline bark (pH 4-7).

Interactions with Other Organisms

• Xanthoria parietina is a lichen, which is a symbiotic association between a fungus and an alga.
• Orange lichens can identify hunting perches of birds.

Quirky Facts

• The orange color of Xanthoria parietina is due to the production of a pigment called parietin.
• Parietin, the orange pigment found in this lichen (and also in rhubarb), is being investigated for its potential as an anti-cancer drug.
• The color of the lichen can vary depending on the amount of sunlight or rain it receives; shaded lichens may appear green, while those in full sun are more vividly orange or yellow.

Further Information

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