Lichen is a pioneer organism that thrives where nothing else can—arctic tundra, hot deserts, rocky coasts and toxic slag heaps, for example. Lichen is intolerant of pollutants; in some European cities, they put lichen stones on rooftops and monitor its health to gauge air quality, mapping what they call "lichen islands."  Photo 8 of 12 in World's First Lichen Garden? by Jaime Gillin

World's First Lichen Garden?

8 of 12

Lichen is a pioneer organism that thrives where nothing else can—arctic tundra, hot deserts, rocky coasts and toxic slag heaps, for example. Lichen is intolerant of pollutants; in some European cities, they put lichen stones on rooftops and monitor its health to gauge air quality, mapping what they call "lichen islands."