Roccella canariensis Darb. em. Vaino
Roccella tinctoria f. valida Hampe ex Darb.
Thallus fruticose, 10-15 cm long, pendent or erect, composed of many branches arising from a single brown to blackish holdfast with a whitish medulla, branches more or less terete, sometimes slightly flattened or distorted from place to place, surface smooth and rather glossy, brown-greenish to brownish when moist, brownish with tinge of purple, brown-greyish when dry. Apothecia button-shaped, more or less numerous, 1-2 mm diam., initially immersed, then sessile, disc flat to slightly convex, covered by a white pruine and then whitish to greyish, exciple thin and inconspicuous, sometimes absent. Ascospores narrowly ellipsoid, straight to slightly curved, 3-septate, 21-27 x 5-6 µm. Photobiont: Trentepohlia. cortex hyphae slightly interlaced, anticlinally arranged but not forming a conspicuous palisade plectenchyma. Cortex: K- or K+ pale yellow, C-, Pd-; subcortex : C+ pale red; medulla: C+ red. Saxicolous species belonging to the Roccellatum canariensis Follm., on coastal rocks in Macaronesian islands. N.B. Some authors consider this taxon as the fertile form of the sorediate Roccella tinctoria. Intermediate fertile and sorediate specimen may be found. N.B. These two taxa have been collected for a long time under thename of Orchilla and used as tinctorial resource to dye tissues in purple-red.
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.