Branched thallus forming small, upright, rounded bushes 3-5 cm high and 5-10 cm in their greatest length, more or less cylindrical twigs with a tapered end, diameter 1-3 mm, from a single base (not yellow), surface smooth with rarely soralia at first rounded and pustular, flattened "like a lens" then becoming globular, whitish and mealy, the coloring of the branches is gray-reddish, gray-orange, greyish a little purple, gray-brownish, brown-orange , etc. Apothecia very rare, 1-2 mm in diameter, black. Spores 3 times septate, 23-27 x 6-8 µm. Photobiont: Trentepohlia. Cortex: K +/- yellow, C + intense carmine red, rapid and persistent, KC+ yellow +/- resd, Pd-, UV-. Rare thermophilic and Macaronesian saxicole taxon coming on the vertical faces very sunny and exposed to the south from the coastal rocks of northern Finistère (Roscoff region) and the northern coasts of Côtes d'Armor, also in the Atlantic Islands always with Roccella fuciformis and Ramalina siliquosa Chem. crassa s.l..
N.B. Strongly resembles Roccella phycopsis but the latter species does not react so intensely in carmine red to C and has more glaucous colorations.
NB "Species" reported from the Ile d'Ouessant in Finistère but the taxon of the region of Roscoff and Primel as well as those of the Atlantic Islands seems slightly different from the taxon of the Ile d'Ouessant which seems to suffer much more from meteorological conditions (wind in particular ) see Roccella tinctoria Taxon Atlantique-Ouessant.
Tehler A., ​​Dahlkild A., Eldenäs P. & Feige G.B. 2004. The phylogeny and taxonomy of Macaronesian, European and Mediterranean Roccella (Roccellacea, Arthoniales). Acta Univ. Ups. Symb. Bot. Ups. 34: 1, 405-428.
