A foliose species with thalli that are small, grey but white-tomentose, rounded like mouse ears, erect and little bullate. The lower surface has cream to light tan veins with simple to bottlebrush shaped rhizines. Young specimens are clearly differentiated by laminal soralia that contain coarse grey soredia which may spread to cover the surface. These soralia disappear as the thallus matures and the specimen will then produce longer than broad apothecia on the end of erect narrow lobes. The margins of the red-brown apothecia are distinctly crenulate.
In Scotland, Peltigera didactyla has a scattered distribution and is found on recently disturbed dry, well-lit soil or sand, such as roadsides, paths, wall tops and dunes. BLS distribution map
scottishlichens.co.uk 