The Distribution of Plants in Perthshire in Relation 
to ‘Age and Area’. 
BY 
J. R. MATTHEWS, M.A., F.L.S., 
Royal Botanic Garden , Edinburgh . 
With two Figures in the Text. 
A RE CENT series of papers from the pen of Dr. Willis has made familiar 
to students of plant-distribution the theory which its author has styled 
4 Age and Area The principle has been fully worked out by Willis from 
the study of numerous floras, and the chief contention, that, on the average , 
the older a species is within a given country the greater area it will occupy, 
is one which is now generally accepted. A review of the hypothesis and of 
its manifest limitations has been given by Willis (1921). 
The applicability of the theory to the flora of Britain may appear 
doubtful, since the effects of man’s occupation are only too well known, the 
action of man being one of the modifying factors emphasized by Willis. 
Nevertheless, an analysis of certain portions of the British flora was 
undertaken by the present writer. The work resolved itself into a 
cartographic study, since the possibility of examining invasions became 
the chief point of interest. From this standpoint, a short paper, illustrated 
by maps, was communicated to Section K at the Edinburgh meeting of the 
British Association for the Advancement of Science, and abstracts have 
appeared in the ‘ Naturalist ’ (November 1921 ) and in the ‘ Journal of Botany ’ 
(January 1922 ). 
A recent communication by Willis and Yule (1922) indicates that the 
distribution of certain local floras and certain groups of British animals 
agrees perfectly with the 4 Age and Area ’ principle. When this paper 
appeared, I had just completed an examination of the distribution of plants 
in Perthshire, and since the facts are available they may serve to illustrate 
how far the hypothesis is applicable to a particularly interesting local flora 
and, at the same time, emphasize the complexity of the problem in so far 
as certain constituents of our flora are concerned. I have not sought to 
deal with size of genera within and without Perthshire. The facts which 
[Annals of Botany, Vol. XXXVI. No, CXLIII. July, 1922.] 
