Did you know that in the 1970s, there were practically no lichens at all in the Edinburgh garden? Today, there are dozens of species on natural and unnatural surfaces alike – from the yellow Xanthoria on Poplar trees and the bushy Usneas on the Azalea lawn, to the pavement dwelling crusts and even a sneaky few tropical imports in the glasshouses. Lichens provide a fascinating window on the world around us – from biodiversity to ecosystem health, and from symbiosis to chemistry. Come join us for a walk through the Edinburgh garden to explore a little about the hidden world right under our noses.