Umbilicaria cylindrica (L.) Delise ex Duby var. cylindrica

    Thallus foliose, to 2-10 cm diam., single or multi-lobed, rounded, wavy, margin with numerous branched black cilia, 3-5 mm long, upper surface wrinkled towards the center, more or less pruinose, grey-whitish, grey, dark grey, tinged-brown, lower surface pale grey-brown with densely packed rhizinomorphs, notably towards the margin. Apothecia usually numerous, more or less globose, 2-4 mm diam., black, gyrose (circularly folded, apparently with several coils). Ascii 8-spored, 50-60 x 15-25 µm according to our measures. Ascospores simple, broadly ellipsoid, , 9-15 x 3-9 µm. Photobiont: chlorococcoid. Medulla : C-, K+/- yellow > red, KC+ red, Pd+ orange. On exposed siliceous rocks, extremely rare in our prospection area due to its mountainous trends. N.B. This species is highly variable and numerous forms and varieties have been described but their validation is questionable. See Umbilicaria crustulosa without black rhizines at the margin and with non-gyrous apothecia.