Roccella phycopsis Ach.
Roccella fucoides (Neck.) Vain.
Thallus shrubby, most often ascending, 3-8 cm tall, composed of terete branches more or less ramified, arising from a single holdfast, beige, pale grey tinged with green,, dull blue-green, orange or bluish. A section towards the base makes visible a faint orange medulla. Branches covered with globose and slightly granulose soralia and spiked with soredia, clustered in small white heaps. Mostly infertile under our climate but it may be possible to find some fertile specimen in the Iroise islands, Western Brittany. Apothecia rounded to oval, protruding, often terminal, disc black, exciple diffuse, irregular and roughly sorediate. Ascospores elongate, narrowly ellipsoid, 3-septate, 18-21 x 4-6 µm (17-27 x 6-8 µm according to our own measures). Cortex with palisade plectenchyma, C+ pink to red, K+ to K+/- yellow, Pd-. Soralia and medulla: C-. Photobiont: Trentepohlia. Rare, on Northern and Eastern dry and vertical walls of coastal large rocks, or on dry walls of chapels. See Roccella phycopsis wall form and less frequently, on bark of deciduous trees in chapel enclosures, Roccella phycopsis bark form. Often found together with Roccella fuciformis of which the branches are flattened and strap-shaped, and much more common in our prospection area. N.B. This species is often subjected to parasites and in that case the colour may be altered and become confusing. Rather variable. It has been related C+ carmine populations, notably in Ouessant island, that may suggest Roccella tinctoria but probably much closer to Roccella phycopsis. See also Roccella tinctoria Taxon Atlantique-Ouessant Cf. and Roccella phycopsis forma.
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.