Parmelia sulcata TaylorThallus foliose, heteromerous, dorsiventral, rather loosely attached, usually forming 4-10(-20) cm wide, distinct rosettes. Lobes sublinear, contiguous to imbricate, elongate, flat, separate, 2-5 mm wide, with truncate apices. Upper surface grey, usually epruinose, rarely faintly white-pruinose in marginal parts, becoming cracked along prominent, elongated pseudocyphellae which give rise to granular soredia arranged in laminal, linear, non-excavated soralia. Lower surface black, with black, simple to furcate rhizines mixed with squarrose rhizines, the latter present also along the margins. Upper cortex paraplectenchymatous, of 2-6 layers of densely packed cells, with a usually non-pored epicortex, the cell walls with isolichenan; medulla white; algal layer continuous; lower cortex paraplectenchymatous, thinner than upper cortex. Apothecia rare, lecanorine, 2-8 mm across, with a brown disc and a usually sorediate thalline margin. Epithecium brownish; hymenium and hypothecium colourless. Asci 8-spored, clavate, <i>Lecanora</i>-type. Ascospores 1-celled, hyaline, ellipsoid, 11-15 x 6-8 µm. Pycnidia immersed, black. Conidia bacilliform, 5-8 x 1 µm. Photobiont chlorococcoid. Spot tests: upper cortex K+ yellow (but often slowly turning orange-red due to medullary substances), C-, KC-, P- or P+ faintly yellow; medulla K+ yellow turning orange-red, C-, KC-, P+ orange, UV-. Chemistry: upper cortex with atranorin and chloroatranorin; medulla with salazinic acid (major) and consalazinic acid (minor).
