Thallus
Foliose, up to 20 cm in diameter, broad rounded lobes that may exceed 1 cm wide, upper surface irregularly wrinkled, especially towards the center of the thallus
Color
Characteristic yellowish-green upperside, black underside
Reproduction
Apothecia: absent
Soralia: generally present towards the center of the thallus, granular, superficial and rather coarse
Isidia: —
Substrate
On bark, sometimes on non-calcareous rock or soil
Occurrence
Very common species except in cold regions
Sensitivity to air pollution
Moderately sensitive to pollution