50 TRANSACTIONS—PERTHSHIRE SOCIETY OF NATURAL SCIENCE. 
3 .—BOTANY. 
The Flowering Plants. 
By the late F. Buchanan White, M.D., F.L.S., F.E.S. 
The banks of the Tay—restricted for the purposes of this paper 
to that portion of the river which extends from Loch Tay to the 
county march at Invergowrie—possess a flora which is not surpassed 
by any other part of Perthshire in richness and interest. 
This very richness makes the subject a somewhat difficult one to 
handle. It would be easy to give a mere list of the species which 
have come under observation, but it seems desirable that something 
ihore than this should be attempted. We have to discover, if possible, 
what effect the physiographical, meteorological, and geological con¬ 
ditions have upon the distribution of the flora. That these conditions 
are potent factors is not to be denied, but in many cases they act in 
combination, and it is difficult to ascertain which of these several 
causes, acting together, is the predominant agent. 
It will therefore be expedient briefly to inquire into the manner 
in which the conditions alluded to affect the distribution of plants, 
and to give a short resume, from the point of view of a botanist, of 
the physiography of the Tay. 
I.—DIVISION OF THE TAY INTO DISTRICTS. 
The course of the river Tay (so far as this paper is concerned) 
may be divided into three sections or districts. 
1. The Highland District where the river runs through compara¬ 
tively narrow valleys, and where the banks either rise at once into 
the hills, or have a fringe of low haughlands liable to inundation 
during floods. 
This section extends from Kenmore to 2 miles below Dunkeld, 
and is about 25 miles in length. 
2. The Strathmore District. Here the river forms a great ditch 
which it has cut through the Old Red Sandstone plain of Strathmore. 
Often the banks are high and rise steeply from the water’s edge to the 
level of the plain above, but, not infrequently, there are low haugh¬ 
lands occupying ground excavated by the river in past ages. 
This section extends from 2 miles below Dunkeld to about the 
mouth of the river Almond, and is about 19 miles in length. 
3. The Tidal District. Here also the river is mostly ditch-like, 
wfith banks of no great height rising steeply to the plain of the Carse 
of Gowrie. The equivalent of the low haughlands of the other 
