Flaking Tarpaper Lichen
Collema flaccidum
Flaking Tarpaper Lichen (Collema flaccidum) is a gelatinous, dark-colored lichen that forms thin, flaky crusts resembling weathered tar paper on its substrate. This cyanobacterial lichen plays a crucial role in nitrogen fixation and serves as a pioneer species in ecosystem succession, contributing to soil formation and providing microhabitat for invertebrates.
Photo: Wikimedia Commons (CC) via https://en.wikipedia.org/wiki/Collema_flaccidum
Taxonomy & Classification
Kingdom
Fungi
Phylum
Ascomycota
Class
Lecanoromycetes
Order
Peltigerales
Family
Collemataceae
Genus
Collema
Flaking Tarpaper Lichen belongs to the family Collemataceae, order Peltigerales, within the Lecanoromycetes class.
Species Profile
Flaking Tarpaper Lichen (Collema flaccidum) is a gelatinous, dark-colored lichen that forms thin, flaky crusts resembling weathered tar paper on its substrate. This cyanobacterial lichen plays a crucial role in nitrogen fixation and serves as a pioneer species in ecosystem succession, contributing to soil formation and providing microhabitat for invertebrates.
Flaking Tarpaper Lichen (Collema flaccidum) is critically endangered primarily due to habitat loss and degradation from urban development, agricultural expansion, and infrastructure projects that destroy the specific rock substrates it requires. Air pollution, particularly nitrogen deposition and acid rain, severely impacts this sensitive lichen species by altering its chemical environment and disrupting symbiotic relationships.
Key Facts
Habitat & Distribution
Collema flaccidum typically grows on calcareous rocks, old mortar, and concrete structures in areas with high humidity and intermittent moisture. It favors sheltered locations such as north-facing walls, cave entrances, and shaded rock crevices where it can access periodic water while avoiding direct sunlight.
Threats
IUCN Red List: Critically Endangered
Flaking Tarpaper Lichen (Collema flaccidum) is critically endangered primarily due to habitat loss and degradation from urban development, agricultural expansion, and infrastructure projects that destroy the specific rock substrates it requires. Air pollution, particularly nitrogen deposition and acid rain, severely impacts this sensitive lichen species by altering its chemical environment and disrupting symbiotic relationships.
Air pollution and acid deposition
Habitat loss from urban development
Quarrying and rock extraction
Agricultural land conversion
Climate change affecting moisture regimes
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). Flaking Tarpaper Lichen (Collema flaccidum). SpeciesRadar: Intelligence for Earth's Biodiversity. Available at: https://speciesradar.org/species/flaking-tarpaper-lichen