Look for Lichens

Clockwise from top left: British Soldier Lichen (Cladonia cristatella), Common Greenshield Lichen (Flavoparmelia caperata), Cobblestone Lichen (Acarospora sp.), Bare-bottom Sunburst Lichen (Xanthomendoza weberi).

Lichens are unique organisms formed by a symbiotic relationship between fungi and algae or cyanobacteria. The fungus provides a structure and protection, while its partner contributes energy through photosynthesis. Formerly scarce in NYC due to air pollution, improvements over the last 50 years have spurred a resurgence of lichens in the city. On iNaturalist there are over 2000 research grade observations of 88 species of lichen in NYC, and thousands more not fully identified. Learn more about the lichens of New York City and help contribute to our knowledge on urban lichens!