142 VEGETATION OF THE PEAK DISTRICT [CH. 
Rubus Chamaemorus Melampyrum pratense 
Empetrum nigrum Galium saxatile 
Erica cinerea Anthoxanthum odoratum 
Calluna vulgaris Agrostis tenuis 
+Azalea procumbens Deschampsia flexuosa 
Vaccinium uliginosum Festuca ovina 
V. Myrtillus Luzula sylvatica 
V. Vitis-idaea L. campestris 
ARE THE PLANTS OF THE CLIFFS AND SCREES LITHOPHYTES ? 
The precipitous faces of the cliffs are tenanted by many 
species of Algae, lichens, liverworts, and mosses; and some of 
these may be regarded as “lithophytes.” Many of the plants, 
however, even the lower cryptogams, are not rooted on the bare 
rock itself, but in the loose soil which accumulates, to a slight 
extent, on the surface of the slight irregularities of the face of 
the rock, even when this is nearly vertical. 
Warming (1909: 238 and 240) uses the term “lithophytes ” 
in a double sense. Section VIII of Warming’s treatise is 
headed “ lithophytes” ; and these are subdivided into (1) “litho- 
phytes” and (2) “chasmophytes.” Warming states that this 
subdivision is in accordance with the suggestion made by 
Schimper (1903—4: 178) who wrote:—“The vegetation on 
the surface of rocks or stones may be termed that of lithophytes. 
Crevices in rocks, in which more finely grained components 
and more water accumulate than on the surface, produce a 
somewhat more copious vegetation, that of chasmophytes.” 
Warming (1909: 240) also cites Ottli who defines as rock- 
plants or petrophytes “all those plants, growing on sides of 
rocks or blocks of detached stone, which are able, as the first 
of their kind, to colonize the rock permanently, and which 
display in distribution or structure a more or less pronounced 
dependence upon rock as a substratum. Within this definition 
are included both lithophytes and chasmophytes.” Ottli (loc. 
cit.) maintains that “it is not a natural scheme to co-ordinate 
both lithophytes and chasmophytes; and he suggests the 
following scheme :— 
