Phytogeographical Excursion in the British Isles. 13 
trees, while in the Loch itself Aponogeton and Nymphaea candida 
grow profusely. In the older plantations of Scots Pine, tall clumps 
of Juniper were conspicuous in open parts, while the usual ground 
vegetation on dry humus included, with Calluna, Vaccinium, etc., 
Trientalis europea, so characteristic of old woods in this district. 
Further off on the hills were seen the woods of Larch extensively 
planted on the Atholl estate over 100 years ago. On the lochs 
special facilities were granted by the Marquis of Tullibardine ; boats 
were available and some members examined the aquatic vegetation of 
these lochs of the “Highland” type. Lobelia Dortmanna was 
abundant, while Jsoétes lacustris, Naias flexilis and other repre- 
sentative species were collected. On the shores of Butterston Loch 
the party passed through a swamp of Alnus with Myrica and Juni- 
perus, fringed on the landward side by abundant Rosa spinosissima. 
The grounds of Dunkeld House were afterwards visited and the party 
were photographed round the stump of the oldest larch in the British 
Isles which was planted in 1738, shortly after the introduction of the 
tree and was killed by lightning in 1906; it clearly shows more than 
160 rings. Dunkeld and its neighbourhood possess a large number of 
interesting exotic conifers many of which were planted shortly after 
their introduction to Europe, and these greatly interested the foreign 
visitors. In the afternoon the party travelled from Dunkeld to 
Aberfeldy and drove thence to Fearnan and Lawers village, on 
Loch Tay, where the night was spent. 
The following day, August 17th, the ascent of Ben Lawers was 
made, the party being joined by Professor Bayley Balfour, who had 
travelled from Edinburgh for the purpose. The route by the Carie 
Burn was taken, and the following zones of vegetation were 
recognised, following Dr. W. G. Smith’s recent account in Types of 
British Vegetation. First the enclosed pastures whose vegetation 
has been influenced by the manuring incidental to pasturage, 
extending from Loch Tay to a height of about 1,000 feet; then un- 
enclosed sheep pastures extending as far as the first ridge of 
moraines (1,500—1,750 feet) and dotted with heather in places. The 
unenclosed pasture passes, on the flat undulating ground between 
the low ridge and Lawers itself, into the grass-moor, which 
is dominated by Nardus stricta and Funcus squarrosus on peat. 
The grass-moor runs a considerable distance up the slope of Ben 
Lawers itself and at a height of about 2,250 or 2,500 feet gives place 
to the first strictly arctic-alpine association, dominated by Alchemilla 
alpina and various grasses, such as Festuca ovina, F. rubra, and F. 
vivipara, Deschampsia flexuosa, and forms of Poa alpina ((2,500-3,500 
feet). This is apparently the culminating association on well drained 
talus slopes. Above this we came to the arctic-alpine chomophyte 
associations of the ledges and fissures of the corries south-west of the 
summit, which were reached by leaving the course of the burn and 
striking obliquely up the slopes covered by the Alchemilla alpina 
association. Above the corries the summit plateau is covered by 
the plant-formation of mountain-top detritus in which mosses and 
lichens, and notably Rhacomitrium lanuginosum, are the pioneer 
and, in the more exposed places, always the leading plants. The 
Swiss botanists recognised in those black crusted tracts and patches 
so characteristic of the summit region, the “schneetälchen ” of 
