freckled pelt lichen

Peltigera aphthosa is a species of lichen known by the common names green dog lichen, leafy lichen, felt lichen, and common freckle pelt. It has a circumpolar distribution, occurring throughout the Arctic, boreal, and temperate regions of the Northern Hemisphere.

This lichen has a large thallus that may exceed one meter in width. It is divided into lobes up to about 10 centimeters long and 6 wide. It is green, becoming pale as it dries. The thallus is dotted with cephalodia, which contains one of the two symbionts, a species of Nostoc. The other is a species of Coccomyxa. These perform photosynthesis, and the Nostoc also fixes nitrogen. The lichen produces large apothecia, a reproductive structure.