common orange lichen, yellow scale, maritime sunburst lichen or shore lichen

Description:

The lobes of the thallus are 1–4 mm in diameter, and flattened down. The upper surface is some shade of yellow, orange, or greenish yellow, while the lower surface is white.

Habitat:

Hardwood forests in low-elevation broad valleys; scattered on Populus and other hardwoods in riparian areas in agricultural and populated areas. It can be found near the shore on rocks or walls and also on inland rocks, walls, or tree bark.

Notes:

Xanthoria parietina is a very pollution-tolerant species.