Flora of Scottish Lakes. 
139 
1909-10.] 
being only 7 or 8 feet, with a maximum of 13 feet. The outline is irregular 
and there is very little shore, merely a narrow strip of rocks or stones 
intervening between the water and the moor or wood ; neither are there 
any sandy bays, but occasionally there is a stretch of peaty shore. The north 
and north-east sides are wooded, chiefly with coniferous trees, and on the 
east there is some cultivated land, otherwise the surrounding district con- 
sists of spongy moor. There are numerous islands scattered over the loch, 
some of which are wooded, and these, with the plantation at the northern 
end, form a pleasing feature in the otherwise bare scenery. In many places 
the bottom is rocky, and at these areas there is no vegetation ; but where 
sand or mud obtains, there is an abundance of plants. The water is 
scarcely peaty, and is so clear that the bottom can be seen through a depth of 
7 feet, even in dull weather. This pellucidity, not only of Mochrum Loch 
but of neighbouring ones as well, is not easily explained, because, from 
their situation in the midst of a spongy peat moor, one would expect the 
water to be quite peaty. The chief feeder is the burn from the adjacent 
Castle Loch ; and as no stream of considerable size enters either loch, pre- 
sumably they are fed partly by springs, which may, of course, have no 
connection with the water of the moor. It is probable, however, that some 
constituent, such as an alkali of the underlying rock, may neutralise the 
peat extract, thus rendering the water clear ; the presence of certain 
calciphilous plants, e.g. Eupatorium Cannabinum, suggests lime also. 
Geologists might find this matter of some interest. A narrow cylindrical 
form of the fresh-water sponge is very abundant at some parts of this loch, 
the dredge occasionally coming up loaded with it. 
The plants that flourish here are as follows : — Littorella lacustris, from 
the margin to 8 feet deep ; Subularia aquatica, from the margin to 6 feet 
deep ; Elatine hexandra, in small patches, from 2 to 8 feet deep ; Isoetes 
lacustris, from 6 to 10 feet deep ; Callitriche hamulata, from 4 to 6 feet deep ; 
Potamogeton pusillus, and a very slender variety of it, extremely abundant 
at from 4 to 10 feet deep ; P. obtusifolius, P. crispus, P. perfoliatus, P. 
natans, Myriophyllum alterniflorum,Fontinalis antipyretica, and F. squamosa. 
All the foregoing were very plentiful, while the following were less so : — 
Lobelia Dortmanna, Chara fragilis, var. delicatula, Nitella translucens, Juncus 
fluitans, Utricularia intermedia, Ranunculus aquatilis, Castalia speciosa, 
Nymphsea lutea, and Sparganium minimum. The marginal flora was rather 
scanty : there were fairly large associations of Phragmites communis, Carex 
rostrata, and Equisetum limosum, while the other species were either in small 
groups or more or less scattered, the chief being — Cladium Mariscus, Phalaris 
arundinacea, Sparganium simplex, Carex filiformis, Ranunculus Flammula, 
