1909- LO.] Flora of Scottish Lakes. 139 



being only 7 or 8 feet, with a maximum of 13 feet. The outHne 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 occasionalh^ coming up loaded with it. 



The plants tliat flourish here are as follows : — Littorella lacustris, from 

 tlie 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 antipja-etica, and F. squamosa. 

 All the foregoing were verj^ plentiful, while the following were less so : — 

 Lobelia Dortmanna, Chara fragilis, var. delicatula, Nitella trans! ucens, Juncus 

 fluitans, Utricularia intermedia, Ranunculus aquatilis, Castalia speciosa, 

 Nymphffia lutea, and Sparganium minimum. The marginal flora was rather 

 scanty : there were fairly large associations of Phragmites counnunis, 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, 



