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Xanthoria parietina: Common Orange Lichen

Xanthoria parietina is a foliose lichen with a wide distribution and several common names.

Common Names:

• Common Orange Lichen
• Yellow Scale
• Maritime Sunburst Lichen
• Orange Wall Lichen
• Sunburst Lichen
• Shore Lichen

Taxonomy and Nomenclature:

• Scientific Name: Xanthoria parietina
• Genus: Xanthoria
• Family: Teloschistaceae
• The genus *Caloplaca* also belongs to the family Teloschistaceae.

Distribution and Habitat:

• Has a wide distribution.
• Common on rocks, concrete, and trees.
• Can be found near cattle farms.
• Common on coastal rocks in New Zealand.
• Observed at Humboldt Lagoons State Park, California.

Morphological Characteristics and Growth Habits:

• Foliose (leafy) lichen.
• Pale- to golden-yellow or orange in color, but can appear grey in shade.
• Lacking isidia or soredia.
• Apothecia (fruiting bodies) are usually present.
• Starts as a small yellow or orange dot and gradually grows outward, sometimes leaving the center white or grey.

Ecological Role:

• Can be prolific, forming an orange lichen belt.
• Grows well on rough, water-retentive, naturally alkaline bark.

Interactions with Other Organisms:

• Orange lichens identify hunting perches of birds.
• They grow in profusion in seabird colonies.

Quirky Facts

• Lichens are described as "dual organisms" because they are a symbiotic association between a fungus and an alga. The alga is contained within the hyphae.
• The orange color of this lichen is due to production of the pigment parietin.

Further Information:

• Katja Schulz has contributed to the "Xanthoria parietina" page.
• Referenced: British Plant Life 3. National Museum of Wales. Orange, A. 1994. Lichens on Trees. A Guide to Some of the Commonest Species
• Referenced: Microchemical Methods for the Identification of Lichens by Alan Orange