Cetraria ericetorum Opiz subsp. ericetorum

      Thallus foliose formed by branched lobes 2-6 cm high, narrow: 1-3 mm in width, folded back on themselves and strongly canaliculated, sometimes forming almost a tube, lobes bordered at the margin of spinules of 0.2- 1 mm, these spinules may have a pycnidia at the tip, upper surface shiny, olive-brown in humid weather, warm brown in dry weather, the base of the lobes being reddish-brown ; lower surface paler with elongated, white pseudocyphellae , mainly grouped in alignments towards the margin. Apothecia very rare at the ends of the lobes, flat disc, brownish. Spores simple, 5-9 x 3-4 µm. Photobiont: chlorococcoid. C-, K-, KC-, P-. Mountain or alpine species coming on calcareous or not very acidic soils of lawns or moors. .

N.B. Very variable species of which several taxa have been described.

See Cetraria islandica subsp. islandica sometimes very difficult to separate, the lobes of which are wider, greener and less canaliculate and which is P + red.