lx PROCEEDINGS—PERTHSHIRE SOCIETY OF NATURAL SCIENCE. 
floor of our river, soils derived from the most diverse sources, and 
varying accordingly in the flora they can support. Along the whole 
course of the river, therefore, we have a fringe of wooding which 
constantly varies in character, and this again differs from the wooding 
which characterises the hill slopes. 
Of the trees which make up the arboriflora of Perthshire, nineteen 
species are believed to be truly indigenous. Leaving out of account 
in the meantime the natural orders to which these belong, we may 
divide them, according to their range of geographical distribution, as 
follows:— 
The holly, gean, crab-apple, crack-willow, and yew have a range 
extending throughout the greater part of Europe and the north and 
west of Asia. 
The bird-cherry, hawthorn, elder, grey sallow, hazel, alder, and 
aspen cover the same territory, but extend also into the north of 
Africa. 
The rowan, birch, and juniper occur in the northern regions of 
Europe, Asia, and North America. 
The ash is confined to Europe and the north of Africa, and the 
wych elm to northern Europe and Siberia. 
The oak occurs throughout Europe and northern Africa, and 
extends eastwards into Asia Minor. 
Lastly, the Scots fir is confined to Europe and northern Asia. 
In addition to these nineteen indigenous species, many other 
trees have become so thoroughly acclimatised that it is difficult to 
realise that they have been introduced by the agency of man within 
historic time. Some of these are indigenous in the southern portion 
of our island, while others have been imported from more southerly 
climates. For example, the elm, the beech, and the lime have spread 
northwards from England; the sycamore has been introduced from 
the Levant, the white poplar from Flanders, the chestnut and the 
horse-chestnut from Asia, the larch from Germany, and the spruce 
from Norway. 
The condition of our county, as regards the distribution of its 
wooding, has varied greatly in times past. At the time of the Roman 
Invasion,—that is to say, at the dawn of the historic period,—it was 
thickly covered with forests, which represented the gradual growth of 
ages, probably commencing with the close of the Glacial Epoch. 
These forests were largely made up of oak, Scots fir, birch, and hazel, 
remains of which are still found in a sub-fossil condition in our peat 
mosses, in the beds of lochs, and in the buried forest bed which 
occurs here and there interbedded with the estuarine clays of 
the Carse of Gowrie. In these forests lived many species of 
mammalia which have long since disappeared from the face of 
Europe, and in them also lived and hunted primeval man, with his 
implements of stone and his dug-out canoes, in which he navigated 
the waterways which intersected the otherwise tractless thicket. 
During early historic times, and especially in the Middle Ages, a 
gradual destruction of these primeval forests took place, the timber 
being used for fuel before coal came into use, and also for building 
the wooden huts in which the people lived. During these ages no 
