When trees get old, they grow soft and more absorbent and develop cracks in the bark. You can often find a good diversity of lichens on trees. The older the tree, the greater the diversity. Notice how different types of lichens grow on different types of trees. They like different growing conditions just like trees and other plants.
Lichens grow slowly but can live to be very old. Reindeer lichens live 30 to 50 years and others live to be thousands of years old! If you see a cool lichen while out on a trail, check it each time you visit. Chances are good you’ll see it again and again.
There are three types of growth forms: crustose looks like it’s spray painted onto the substrate surface, foliose is leafy, and fruticose is bushy or shrubby. Take a hand lens or magnifying glass to look even closer. The lichen body (or thallus) is often a different color on top than it is underneath on the leafy varieties. These variations can be ways to identify one species of lichen from another.
While you’re looking close, check for disks or cup-shaped structures (apothecia), surface granules (soredia) and other small growths (isidia) - these are structures that produce and distribute spores. They are also another way to identify the different species of lichens.
Have fun while you’re out hiking, skiing or snowshoeing and stop every now and again to look at the lichens. They’ve always been right there in front of us but often go unnoticed. During the winter when other vegetation forms are covered, lichens are waiting for us to notice them.