Cladonia cervicornis (Ach.) Flot.

    Primary thallus made of basal squamules forming cushions up to 15 mm high, 5 mm long, ± rounded, sometimes nodulose and swollen or with margins indented, reflexed when dry, like flower bud (chrysanthemum flower). Upper surface green-blue, green-grey, grey-brown to green; lower surface white, greyish, sometimes tinged pink or mauve notably towards margins but not black nor dark towards the base. Podetia more or less abundant, to 1 cm tall, with shallow ± regular scyphus, without proliferation towards the center or margins and limited to one level, sparingly squamulose or smooth, without soredia. Apothecia as nodulose extensions on scyphus margin, brown, brown-red. Photobiont : trebouxioid. C-, K-, KC-, Pd+ red. Prefers basic coastal dunes (but not too calcareous), also on soil near the seashore and inland. See  Cladonia subcervicornis, very similar but much darker grey, K+ yellow and Pd+ red and also Cladonia verticillata of which the podetia form proliferating tiers in 2 or more levels from the center, Cladonia pulvinata very close to Cladonia verticillata but P+ bright yellow, and mainly Cladonia firma which displays larger squamules markedly recurved at apices when dry, lower surface grey-violet and K+ yellow, very eldom fertile. N.B. This species is highly variable and may encompass several taxa (that were differently analysed by various authors). Seldom isolated and more often together with other Cladonia species thriving in the same habitat. We can separate a form coming from the top of cliffs exposed to spray Cladonia cervicornis forma which is characterized by its rapidly brown colorings, the abundance of its podetions whose cups are bordered by pycnidia and apothecia and having a strong tendency to proliferate from the center (but on one level).