1909-10.] Flora of Scottish Lakes. 127 



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 poh'-o-oni- 

 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 Brj^ophytes 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 Hora. 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 sand}^ 

 shore in one season, probably by black-headed gulls. On the other liand, 

 I have observed new additions to the flora of a loch which were probably 

 introduced there by birds. Such clianges amongst the minor plants of a 

 loch are no doubt constantly occurring (p. 152). 



II. — Area Y. 



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 \ 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 rock}'' and stonj', with 

 only a few plants. On the south-west side there is an extensive marsli, 

 now partially drained (fig. 46). The west, north, and north-east sides are 



