From the Arctic to tropical rain forests, lichens exhibit a wealth of colors and shapes, grow on rocks, bark, and barren soil, and are sensitive indicators of environmental change. James Lendemer, Assistant Curator of Lichenology at NYBG, has studied lichens for more than a decade, documenting their biodiversity, how they have become threatened, and ways to protect this key member of many ecosystems. He provides a fascinating look at this complex amalgam of fungi and algae followed by a lichen expedition through our naturalistic gardens. Dress for the weather.