Umbilicaria polyphylla (L.) Baumg.
Thallus foliose, to 3-10 cm diam., multi-lobed, lobes thin, delicate, 1-2 cm tall, wavy, lobe margins wavy, ascending, irregularly lacerate, upper surface smooth, dark brown, brown-blackish, lower surface blackish, smooth without rhizines. Apothecia very rare, gyrose, 0.5-1.5 mm diam., disc black, margin thick, black. Ascospores simple, elongate ellipsoid, 12-19 x 4-8 µm. Photobiont: chlorococcoid. Medulla : C+ red, K-, KC+ red, Pd-. Mountainous trends, very uncommon in our prospection area, on highly exposed siliceous rocks. N.B. Highly variable species. Numerous described varieties are more or less validated. N.B. See Umbilicaria polyrrhiza with rhizinomorphs on lower surface. Notice also that the old specimen of Lasallia pustulata, much more common in the same habitat, may have bloated lobes with isidiate margins.*