You may not realize it but there’s a good chance your trees have a funny little friend living in them, a growth called ‘lichen.’ Although some of you have just noticed them, they’ve been around for hundreds of millions of years and can be found all over the world in almost every habitat. They grow on a variety of animate and inanimate objects in nature from rocks and trees to sides of barnacles. Sometimes even insects will be covered in lichen to use for camouflage, but only in the proper hunting season.
People tend to notice lichens growing on the sides of their trees and mistake them for fungus, and they are only partially wrong (also partially right! – good job). Lichens are a composite of 2 organisms that make up this symbiotic/mutualistic structure, that’s part fungi and part algae. There is usually one type of fungus and there can sometimes be 1-2 types of algae, but the species of lichen is always identified by its fungal partner. Although the 2 organisms exist together harmoniously, some scientists believe the relationship to possibly be more parasitic in nature. Just when you thought you knew your ‘partner’…
Lichens do not have roots or branches to take in water, so they gather everything they need from the sun and air, causing them to be very susceptible to the quality of the air. There are thousands of species of lichen that come in a variety of colors, and some are a little more tolerable to the poor air quality than others which allows for a quick color guide to what quality air you are breathing. The yellow Xanthoria species should throw caution to the wind that you are experiencing higher levels of pollution. I wonder what the red lichen indicates!
So don’t fret about some of the splotches of color on your tree, it’s probably just a really cool little lichen growth that’s just vibing, not hurting anything. If you’re not sure it is, you can always call out an arborist to inspect and confirm what’s going on with your tree. We always like an excuse to look at neat stuff!