Common on maples, especially bigleaf maples, like the one in the pictures in my garden. urban or forest.
Around mid-August islands of small black spots (structures that will produce sexual spores the following spring) surrounded by yellowish tissue develop on the living leaves. Later in fall when the leaves have turned golden and mostly fallen, the "tar spots" can be seen surrounded by a circle of green tissue that remains photosynthetic long after ihe leaves have fallen to the ground. The fungus overwinters in the dead leaf and, in the spring, releases spores that are transported by the winds to infect new young leaves.