Lacy Lemon Lichen
That patch of yellow
Since I started noticing lichens, I've been finding them all over the place. On stone walks, on old buildings, and all over the trees. Every twig that falls to the path in the woods seems to be covered with them. Tree trunks have patches of color that upon a close look turn out to be lichen.
One that I find a lot on tree trunks is a purely yellow color. The texture is so fine that I can't see details without my loupe. Sometimes I take a twig home and look at it under the microscope. Then I can see a bit more of what is going on.
Identifying the lichen
There are so many kinds of lichen that I seldom find one that matches in my little field guide to lichens. Sometimes I can work them out with a key, which examines the details and narrows down the possibilities. It's often difficult. Many lichens have characteristics that are not easily seen even with a microscope and that require chemical tests that are beyond my experience and equipment.
However, when I used a key to identify this yellow lichen, I was pleasantly surprised. It was simpler than most, and the answer came out in just a few steps.
Here are the identifying characteristics. It's a lichen in Iowa on tree bark. Under the microscope, it looks as if it's made of miniature lettuce leaves. (They are not actually leaves, however. The term is lobes.)
It's very tiny. Everything in the top photo would fit on your littlest fingernail.
The color is lemon yellow, with no trace of orange.
Along the edges of the lobes are microscopic balls ("soredia") which can drift off to make new lichens. These give the lichen its lacy look.
The yellow top side is different in color and texture from its paler underside.
No other life form is all of those things. This being has the scientific name of Candelaria concolor. Its friends may call it Lacy Lemon Lichen.
Why is it fun?
I enjoy working out a lichen's identity with a key. The key guides me to notice things about the lichen that I would not have seen. I might have missed out on Lacy Lemon Lichen entirely, seeing only a yellow blur on a tree trunk, if I even noticed that.
— Diane Porter, Fairfield, Iowa, February 12, 2022