Black-eyed Rosette Lichen
Physcia phaea
The Black-eyed Rosette Lichen (Physcia phaea) is a foliose lichen species characterized by its distinctive rosette-like growth pattern and dark, eye-like reproductive structures (apothecia) that contrast against its grayish thallus. This epiphytic lichen forms circular patches on tree bark and plays an important ecological role in nutrient cycling and providing microhabitat for invertebrates.
Photo: iNaturalist: (c) Hans Ritter, some rights reserved (CC BY-NC), uploaded by Hans Ritter
Taxonomy & Classification
Kingdom
Fungi
Phylum
Ascomycota
Class
Lecanoromycetes
Order
Caliciales
Family
Physciaceae
Genus
Physcia
Black-eyed Rosette Lichen belongs to the family Physciaceae, order Caliciales, within the Lecanoromycetes class.
Species Profile
The Black-eyed Rosette Lichen (Physcia phaea) is a foliose lichen species characterized by its distinctive rosette-like growth pattern and dark, eye-like reproductive structures (apothecia) that contrast against its grayish thallus. This epiphytic lichen forms circular patches on tree bark and plays an important ecological role in nutrient cycling and providing microhabitat for invertebrates.
Black-eyed Rosette Lichen faces severe decline primarily due to air pollution, particularly nitrogen deposition and sulfur compounds that alter its substrate chemistry and disrupt its symbiotic relationship. Habitat loss from urbanization and agricultural intensification has eliminated many suitable sites, while climate change is shifting precipitation patterns and temperature regimes beyond the species' tolerance limits.
Key Facts
Habitat & Distribution
Physcia phaea grows primarily on the bark of mature deciduous trees, particularly favoring species with neutral to slightly basic bark pH such as ash, maple, and oak. It typically occurs in areas with high humidity and clean air, often found in old-growth forests and well-established parklands with minimal atmospheric pollution.
Threats
IUCN Red List: Endangered
Black-eyed Rosette Lichen faces severe decline primarily due to air pollution, particularly nitrogen deposition and sulfur compounds that alter its substrate chemistry and disrupt its symbiotic relationship. Habitat loss from urbanization and agricultural intensification has eliminated many suitable sites, while climate change is shifting precipitation patterns and temperature regimes beyond the species' tolerance limits.
Air pollution and nitrogen deposition
Habitat loss from urbanization
Agricultural intensification
Climate change impacts
Substrate degradation
Community Sightings
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Sources & Attribution
How to Cite
IUCN: IUCN (2025). The IUCN Red List of Threatened Species. Version 2025-1. Available at: https://www.iucnredlist.org. doi:10.2305/IUCN.UK.2025-1.RLTS
GBIF: GBIF.org (2025). GBIF Home Page. Available at: https://www.gbif.org
This page: SpeciesRadar (2025). Black-eyed Rosette Lichen (Physcia phaea). SpeciesRadar: Intelligence for Earth's Biodiversity. Available at: https://speciesradar.org/species/black-eyed-rosette-lichen