Peltigera canina (L.) Willd.
Thallus foliose, to 20 cm across, lobes up to 3 cm wide, thick and flexible, rather short, surface bullate owing to conspicuous flattened veins, margins down-turned, in some cases showing the tooth-like tips of veins (reference to the name of this species); upper surface greyish, grey-brownish, beige when dry, almost entirely whitish and tomentose, lower surface whitish with thick 'woolly' veins, rhizines abundant, crowded, variable in shape and size, mostly in confluent tufts, highly branched, pointed, brush tip like. Apothecia scarce, saddle-shaped, disc flat then slightly concave, brown-reddish, dark brown to black. Ascospores fusiform, 3-5-septate, 42-53 x 2.5-5.2 µm (according to our observations, mean : 40-45 x 3.5-4 µm). Chemical spot tests negative. Rather common on dry calcareous or slightly acid dunes with low vegetation, also found inland on slightly acid grounds. Not to be confused with Peltigera membranacea of which the tomentum is limited and rhizines scattered, and with Peltigera rufescens of which the rhizines (notably towards the center) are blackish and lobe margins crinkle.*