Peltigera polydactylon

On soil or moss-covered rocks, with lobes having a greenish-blue upper surface and brown lower surface with abundant rhizines that anchor it to the substrate; saddle-shaped apothecia at the lobe tips, dark brown to reddish brown.

Photobiont with cyanobacteria of the genus Nostoc.

Asci cylindrical-clavate, eight-spored, 80 to 105 µm long, 9 to 11 µm wide, with spores arranged parallel to each other inside the ascus, and a strongly amyloid apical apparatus in Melzer's reagent.

Paraphyses filiform, generally simple, multiseptate, hyaline, 2 to 3 µm wide, with slight apical enlargements up to 4 to 5 µm, brown apical pigments responsible for the apothecial color, extending only very slightly above the asci.

Ascospores acicular, cylindrical, straight to slightly curved, smooth, hyaline, thin-walled, 45 to 70 µm long, 3.5 to 5 µm wide, mature ones with three faintly visible septa, containing a dense mass of small oil droplets (guttules) inside.