Flora of Scottish Lakes. 
127 
1909-10.] 
grass-like associations, Molinia cserulea being the most abundant. The 
dominant plants of these lochs are as follows : — Subularia aquatica, Lobelia 
Dortmanna, Littorella lacustris, Isoetes lacustris, Scirpus fluitans, Juncus 
fluitans, Glyceria fluitans, Fontinalis antipyretica, Potamogeton polygoni- 
folius, P. natans, Scirpus lacustris, Phragmites communis, Equisetum 
limosum, Heleocharis palustris, Carex rostrata, C. flava, Juncus acutiflorus, 
J. lamprocarpus, J. effusus, Menyanthes trifoliata, Eriophorum polystachion, 
E. vaginatum, Ranunculus Flammula, and the Bryophytes and lower 
Cryptogams already mentioned. 
In the paucity of species which comprise their flora, the three last- 
mentioned lochs agree with those on the Merrick range a few miles to the 
west. The scarcity of water-birds about these and other mountain lochs 
is probably a factor to be considered when forming a theory to account for 
the poverty of species in their flora. Doubtless mountain lochs offer an 
inhospitable asylum to the majority of our water-fowl. That such birds 
are active agents in the distribution of aquatic plants is beyond doubt. 
They are also great destroyers of the less robust vegetation, especially in 
shallow water, and are frequently the cause of the sudden disappearance of 
an association of small plants from some particular part of a shore. To cite 
examples, I have known Scirpus setaceus quite obliterated from a sandy 
shore in one season, probably by black-headed gulls. On the other hand, 
I have observed new additions to the flora of a loch which were probably 
introduced there by birds. Such changes amongst the minor plants of a 
loch are no doubt constantly occurring (p. 152). 
II.— Area V. 
Having now passed, by means of a circuitous and zigzag route, over the 
majority of the lochs situated in N.W. Kirkcudbrightshire, where the 
highland type predominates, let us leave this “ Land of the mountain and 
the flood ! ” and beginning at Loch Corsock, examine S.E. Kirkcudbright- 
shire (p. 66), where many of the lakes are lowland in character. 
Loch Corsock is a somewhat triangular sheet of water, about J mile 
long, situated in an upland district, whose moorland character has been 
modified by cultivation. It lies about 6 miles north of Crossmichael, 
at an elevation of 540 feet above sea level, and the water is somewhat 
peaty. The western shores are flat and muddy or peaty, and have an 
extensive vegetation, whilst the eastern shores are rocky and stony, with 
only a few plants. On the south-west side there is an extensive marsh, 
now partially drained (fig. 46). The west, north, and north-east sides are 
