34 floristic releves concerning epilithic lichens have been carried out in 6 archaeological sites in the surroundings of Rome, on different types of substrate. 52 lichen species have been recorded.
The matrix of the releves and of the species has been submitted to programs of multivariate analysis (classification and ordination); the results allow to distinguish 5 main community-types and to order the species according to their degrees of acidophytism and nitrophytism.
