Peltigera horizontalis (Huds.) Baumg.

    Thallus foliose, to 30 cm across, lobes 1-3 cm wide and 3-5 cm long, margin upturned and slightly crisped, upper surface smooth and glossy, grey-greenish to grey-bluish when moist, brownish when dry, lower surface very pale brown to whitish towards the margins, darker towards the center, with more or less anastomosed veins, brown blackish, delimiting in between oval or circular white sections, rhizines fasciculate, in brooms, clustered and ordered in concentrical rings. Apothecia rounded, occasionally broader than long, 4-8 mm diam., typically dish-like, horizontal, disc red-brown, exciple uneven. Ascospores fili-fusiform, 3-septate, 30-46 x 3-7 µm. 27-47 x 4-7 (8) µm according to our measurements. Chemical spot tests negative. On mossy trunks of trees in old woodlands, mainly near the ground or at the trunk base.*