Learn / Ask The Landscape Professional
I've had this dogwood tree for over 20 years and it seems to be fine. However, in the last several years I've noticed this growth on it. I'm assuming that it's some sort of lichen. Is this anything I should be concerned about? Maureen
Answer
You have Lichen growing on your tree. It is completely harmless and there is no
need to get rid of it. 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. Around the world, as
far back as Roman times, lichens were used as dyes for fabric and in healing
ointments. Lichens have even been found inside Egyptian mummies from 1500BC! Since
the 1300's, lichens have been the main source of dyes used in litmus paper, a paper
testing strip used to determine pH. Today, they are used in perfumes and in dried
flower arrangements as well as for miniature plant representations for model railroads.
Lichen will only grow in areas 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.
