My friend Peter Schmidt was visiting Germany recently and found this tree branch in a woodland area. He thoughtfully shared it with your local Lichen Hunter. I have no idea what it is, but am going to spend some time with my lichen resources to challenge myself.
On the left there are some distant branches with yellow lichen; a careful look around this woodland might find more interesting species in addition to these bright yellow ones.
Here’s a closer view. Although the resolution is not good enlarged, we can see it is a foliose type of lichen; it has some leafy growth in areas and looks wrinkled, as if it is not tightly attached to the branch, as a crustose lichen would be.
Last summer I posted images from British Columbia, Canada, of the yellow lichens that are very common there in the fir and spruce forests.
The Letharia is a fruticose type lichen; it has branches, grows upright or trailing and is attached to the tree at small, discrete spots, just like a shrub growing in the ground.
Letharia vulpina uses vulpinic acid to make the yellow color, which is poisonous. In some parts of the north it has been used as a poison to kill wolves and other animals. It is toxic to any meat-eating mammal, as well as to molluscs and insects. But it does not affect mice and rabbits! The lichens use vulpinic acid to control the amount of light absorbed. (Lichen Biology, Thomas H. Nash III). The German lichen may use a different chemical to make its yellow color; a mystery I won’t solve today.
Remember, look for the Tiny Ones when you are out walking.