Peltigera rufescens (Weiss) Humb.
Thallus foliose, to 20 cm across, rosette-forming or fragmented, lobes to 4 cm long and 0.5-1 cm wide, breakable, tightly appressed to the ground with only the margins upturned, crinkled or crisped, upper surface sometimes slightly embossed, pale greyish and delicately tomentose towards the margins and sometimes frosty, colour highly variable according to hydration: greyish, brown-greyish, brown-reddish, reddish; lower surface brown-black towards the center, paler or whitish near the margins, more or less bullate with dark veins, rhizines coalescing at their base in small tufts, well-developed, greyish, dark-grey or blackish towards the center, smaller and whitish towards the margins. Apothecia saddle-shaped, as wide as tall, erect, emerging from lobe margins, exciple crenulate, denticulate, folded, brown-red. Ascospores markedly elongate, 3-5-septate, 40-70 x 3-5 µm. On dry calcareous and well-lit dunes, often together with Peltigera canina which is often confused but with rhizines white and brush-forming, sometimes also with Peltigera membranacea or Peltigera hymenina. N.B. This species shows intermediate traits with the other species mentioned here and sometimes it is rather difficult to make a decision. Apothecia and habitat seem to be the most relevant criteria.*