Calcareous, often petrifying, springs. Their specialized communities, usually dominated by bryophytes, belong to the Cratoneurion commutati. Characteristic species are the mosses Cratoneuron filicinum, C. commutatum, C. commutatum var. falcatum, Catoscopium nigritum, Eucladium verticillatum, Gymnostomum recurvirostrae, with Equisetum telmateia, E. variegatum and flowering plants including Cochlearea pyrenaica, Arabis soyeri, Pinguicula vulgaris, Saxifraga aizoides. The associated swamp communities belong to the Caricetalia davallianae and their presence can be recorded by the use, simultaneously with one of the codes of 54.12, of a code of 54.2. Large petrifying springs form tufa cones that constitute singular habitats with several interacting plant and animal communities; they have thus been individualized below.