A foliose species with a chestnut to dark brown thallus that is usually glossy and looking as if varnished. The branches are somewhat flattened and usually have white pseudocyphellae in depressions, especially near the axils. The branches terminate in short, blunt spines which may also be present on the main branches. It often grows in interwoven mats.
Thallus: C-, K-
Cetraria aculeata is widespread in upland Scotland where it is found on heaths, stabilised shingle and acid sand dunes. BLS distribution map
Cetraria aculeata is distinguished from Cetraria islandica by the narrower lobes that look flattened and furrowed from above.
scottishlichens.co.uk 