Do you ever walk past an old building or a tree or a big rock and notice splotchy green or orange or yellow blobs growing all over it? Well, these are probably lichens! Lichens aren't plants and they aren't even technically just fungi. They are actually many organisms living together and functioning as one unit. These "composite" organisms are fungi with symbiotic algae or cyanobacteria living inside them, providing them with sugars produced by photosynthesis. On this episode, Dennis Waters explains what lichens are, why we see them everywhere, what they do, and even what they taste like! We cover topics from symbiosis, to climate change to lichens living in space, suspended outside of the International Space Station. Dr. Dennis Waters, PhD is a lichenologist and is currently a visiting scientist at the Chrysler Herbarium at Rutgers University. He is also an author and his book "Behavior and Culture in One Dimension: Sequences, Affordances, and the Evolution of Complexity" is available here or on his website.Dennis has also provided some links to resources if you want to learn more about lichens:

• North American Lichen Checklist
• Database of Lichens in North American Herbaria
• Catalog of research papers on lichens
• Some helpful books: Urban Lichens (this is the one I have), Lichens of North America, Delmarva Lichens: An Illustrated Manual, Field Guide to the Lichens of Great Smoky Mountains National Park, Common Lichens of Northeastern North America, and The Macrolichens of New England
• Some images: source 1, source 2, source 3

Music is "Introducing Cosmic Space" by Elf Power and "Vorticella Dreams" by L. Felipe Benites.