The Lichen on some of our trees has grown unsightly...and looks harmful to the tree(s). We had been told years ago that the Lichen was of needless concern but now it is also on neighboring rock wall, etc. Is this unhealthy for family residents and trees? Should we try to remove? Would appreciate your expert opinion? Thank you. Janice
Answer
Dear Janice,
Your question is the one I get asked most often. The lichen you have growing on your tree and rock walls is completely harmless and there is no need to be concerned. Lichen is a unique organism because it's not just a fungus, but an alga as well that lives with the fungus symbiotically (when two different kinds of living things live together and depend on each other). The fungus part of lichen collects moisture which the alga needs and the alga creates food made from the energy of the sun for the fungus. Lichen is found in many places like on trees and rocks; in gardens they look wonderful on landscape rocks. Lichens are completely harmless to trees and although they are attached to the tree bark by "rhizines" which are hair-like roots, they do not penetrate deeply enough to cause any concerns. Lichen grows slowly and likes undisturbed surfaces, so you won't see it on species of trees that shed their bark frequently.
Different forms of lichen have been all over the world for centuries, including the Artic and Antarctica. There are more than 15,000 types of lichen and estimates run as high as 6% of the earth surface is covered by lichen. Lichen will only grow in places where the atmosphere is clean, so it's a good sign and you can be happy that you have them growing on your property!
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About Linda Lillie
Linda K. Lillie is the President of Sprigs & Twigs, Inc, the premier
landscape design and maintenance, tree care, lawn care, stonework, and carpentry
service provider in southeastern Connecticut since 1997. She is a graduate of
Connecticut College in Botany, a Connecticut Master Gardener and a national
award winning landscape designer for her landscape design and landscape installation work.
