Epiphytes and Epiliths

Abstract

Epilithic or saxicolous bryophytes may be defined as those growing directly on the surface of rock, and in this chapter do not include aquatic species; epiphytic or corticolous species are those growing on the bark of living trees and shrubs. In the literature, authors dealing with epiphytes usually adhere strictly to the above definition, probably because of the well-defined nature of the habitat, although a few (e.g. Barkman, 1958) include species on dead tree stumps and logs. On the other hand, and this makes the interpretation of some data difficult, the term saxicolous is often taken (e.g. Yarranton, 1967a) to include plants growing on soil or detritus overlying rock as well as those occurring directly on rock surfaces. In the account of epiliths in this chapter the strict definition is followed as far as possible. There has been considerably more work done on epiphytes, especially of a phytosociological nature than on epiliths. There are probably several reasons for this — the epiphytic habitat is much more discrete and the number of species involved is usually much fewer (see, for example, Table 7.1).