84 FLORA OF ARROCHAR MOUNTAINS. 
greater or smaller amount of humus, the quantity of moisture, or 
(to a lesser extent) the exposure and altitude. 
The following list of plants forming the grass association will 
shew that it does not differ in any respect from that characteristic 
of Scottish hill-pasture in other districts. This particular list 
represents the species present on a piece of dry ground at an 
altitude of 2,c00 feet on Ben Narnain, and may be said to be 
fairly typical of the hill-side vegetation throughout the district. 
The species are arranged in the order of numerical importance — 
not in systematic order :— 
Anthoxanthum odoratum. Luzula campestris. 
Aira flexuosa. Vaccinium Myrtillus. 
Festuca ovina. Potentilla tormentilla. 
Nardus stricta. Carex (sp.) 
Galium saxatile. Juncus squarrosus. 
The principal dominant species in the grass association are the 
following four, viz. :—Azra flexuosa, Nardus stricta, Anthoxanthum 
odoratum, Scirpus cespitosus. These four replace one another 
over the greater part of the moors—now one, and now another 
taking the dominant position. Other plants also become domin- 
ant in more restricted areas, such as _/umcus sguarrosus, or, in very 
wet places, Juncus acutifiorus. ‘The secondary species, of course, 
vary greatly in numerical importance at different points, but, 
although differing in relative numbers, the same species are pretty 
constant throughout. ‘The following list may be compared with 
the one already given. This represents a similar association on 
Ben Vane at 1,400 feet altitude (six hundred feet lower than the 
one selected on Ben Narnain)— 
Aira flexuosa. Molinia czrulea. 
Luzula campestris. Galium saxatile. 
Scirpus czespitosus. Juncus squarrosus. 
Nardus stricta. Anthoxanthum odoratum. 
Potentilla tormentilla. 
The presence of the Molinia in this list, and its absence from the 
former, which is the most striking difference, is not due to the 
difference in altitude, for this grass is common all over the moors, 
and forms part of the plant-carpet on the summits of Ben Vane 
and Ben Vorlich—both over 3,000 feet. 
