One of my lichen books calls these blister lichens. The other one calls them star rosette lichens.
Their scientific name is Physcia stellaris.
Black is the most common blister lichen I find here in southern Illinois.
Some blister lichens have brown discs,
and others have green.
The discs are called apothecia and are where the spores are produced.
Then I found a blister lichen with gray discs in the backyard yesterday.
Now I wonder what other colors that I might find?
naturesnippets 