thallus_surface_granulose
granules
initiated by very small granules; first visible as isodiametric structures c. 20-60 µm wide; structures increase in size to form dorsiventrally flattened, more or less circular, rosette-like patches with a minutely crenulate margin; patches coalesce with neighboring ones to form a diffuse crust which is uncracked or has sparse secondary cracks; healthy layers often overlie older layers, which are partly dead or contain abundant brown pigment
Verrucaria rosula
Verrucaria rosula