Article

The bryophyte vegetation carpeting the traditional macadam alleys of IO historical gardens in the city of Palermo, and its variation as a function of different microenvironments, have been analysed. Four types of communities can be distinguished, ali pertaining to the class Barbuletea unguiculatae. The first, characterized by Scorpiurium circinatum, occurs on areas relatively undisturbed by trampling, on more heavily trampled, moister ground a community with Riccia crystallina and Sphaerocarpos michelii predominates. Two closely related communities occur where a soil layer covers the macadam: one in more sunny situations where substratum is frequently disturbed and heterogeneous, in which Didymodon vinealis, D. luridus, and Aloina rigida prevail; the other on more compact, drier soil, where the dominant species is Riccia lamellosa. The bryophyte flora of these man-made habitat is of considerable interest owing to the presence of some rare species, and warrants conservational efforts to be made in view of its preservation.