Pulmonary lichen (Lobaria pulmonaria) in the Vercors. A large foliaceous lichen - one of the largest in Europe - whose thallus commonly exceeds about 30 cm. Like all lichens, it is a lichenised fungus, and like most of them it belongs to the ascomycetes group. Its membership of the cyanolichen category, fungi associated with cyanobacteria, makes it a particularly sensitive organism to atmospheric pollution. It is therefore a species in decline in many regions and has been chosen as a health index for French forests. Ambel forest, Vercors NRP, France