240 TRANSACTIONS—PERTHSHIRE SOCIETY OF NATURAL SCIENCE. 
XXIV.— The Geological Factors in the Distribution of the 
Alpme Plants of Perthshire. 
By Peter Macnair. 
(Read 14th April, 1898.) 
The problem of the distribution of our alpine plants is one which 
has attracted from time to time the attention of many of our leading 
botanists, though up to the present moment it can scarcely be said 
that any satisfactory answer has yet been given to this difficult question. 
The fact that on certain of our Highland mountains, such as Ben 
Lawers, Canlochan, Ben Lui, and others, there are to be found many 
species of alpine plants whose native habitat is supposed to have been 
the Scandinavian mountains, and which are now mostly confined to 
Lapland, Norway, and the Alps, has long been recognised. The 
Breadalbane mountains were first explored by Lightfoot and Stuart 
about the year 17 73 ) while in 17 79 ) we find Don making excursions 
into the Highlands of Forfarshire and adding considerably to our 
knowledge of the existence of alpine species on these mountains. 
Since then, these mountains have been carefully searched by many 
of our leading botanists, the result being that we have now quite an 
exhaustive knowledge of the different alpine plants which grow upon 
them, and the different stations where they are to be found. As the 
late Dr. Buchanan White has pointed out, it is a remarkable fact that 
Stuart does not seem to have ever visited Ben Lawers though he was 
well aware of the richness of the Craig-na-Caillach and Meall-nan 
Tarmachan ridge, and had visited more distant mountains than Ben 
Lawers in his botanical searches. Ben Lawers does not appear to 
have become known till towards the end of the last century, and, as 
we have already pointed out, it was between the years 1779 and 1812 
that Don made that remarkable addition to the list of British plants, 
mainly from the Clova mountains, whose botanical treasures he was 
the first to reveal. About the year 1873, another valuable addition 
to the list of stations for these plants was made in the discovery, by 
Dr. Buchanan White and Colonel Drummond Hay, that Ben Lui 
was exceedingly rich in alpine flora. Such, then, is a brief notice 
of the discovery of these localities, and when we come to inquire 
into the geological factors in the distribution of these plants we 
shall be better able to appreciate their significance, for we shall 
see that they are not distributed at random, but according to certain 
geological laws which were in operation directing the lines of plication 
into which the Highland rocks were thrown during the great process 
of mountain building. 
The problem of the distribution of these alpine plants may 
