Cetraria aculeata (Schreb.) Fr.
Thallus forming small shrubby and thorny-like tufts (during dry weather), to 5 cm high, spreading loosely without apparent order, seemingly little attached to the substratum (when moist), highly ramified, branches irregular in section, main branches to 1 mm diam., sharp tips prickle-like, surface glossy shine, chestnut, dark-brown, brown-redish, brown-greenish, pitted with pseudocyphellae, concave, and elongate, whitish, usually present in pits and at ramification levels. Apothecia scarce, 2-5 mm diam., disc concave, then convex, concolourous with the thallus, exciple with small spinules. Photobiont : Trebouxia. Chemical spot tests negative. Probably rather common but unnoticed, on coastal acidic sand-dunes amongst Calluna or dry heathlands, often together with Cladonia portentosa s. l.. Coastal trends in Brittany. N.B. This species shrivels up when dry and becomes hardly visible amongst plant debris.*