The White Moss Loch. 
M3 
Vicia cracca f. 
Lotus uliginosus f. 
Geum rivale f. 
Scabiosa succisa f. 
Mentha aquatica var. major f. 
Achillea Ptarmica o. 
Briza media o. 
Dactylis glomerata o. 
Orchis mascula r. 
Listera ovata r. 
The following are frequent species which have probably come 
in from the surrounding arable land :— 
Senecio Jacobaea f. 
Centaurea nigra f, 
Plantago lanceolata f. 
Cnicus arvensis f. 
Bartsia Odontites f. 
Euphrasia officinalis f. 
Rhinanthus Crista-galli f. 
The following is a summary of the plant communities distin 
guished in the vegetation of the White Moss :— 
I.—Aquatic Formation. 
(A) . Deep water association. 
(B) . Shallow water association. 
(C) . Reed-swamp association. 
(a) Phragmites communis consoctes. 
(b) Carex ampullacea consocies. 
II. —Marsh Formation. 
(A) . Herbaceous marsh association. 
(a) Carex-Menyanthes sub-association. 
(b) Comarum palustre sub-association. 
(B) . Alder-Willow association. 
Distribution of the Plant Communities and the 
Determining Factors. 
In considering the factors which have determined the plant 
distribution, the chemical constitution of the soil and water may 
he regarded as remaining fairly uniform throughout, since there is 
no inflow stream, there is no differentiation of soil salts or of 
aeration between different parts of the loch. Lime is present in 
the water to a small extent and the decaying vegetation in itself 
returns nutriment to the soil. There seems to he sufficient evidence 
for regarding the main determining factors as entirely biotic. 1 
In the aquatic formation, only submerged plants occur in the 
deepest water, but the accumulation of their debris results in a 
shallowing of the water and in the shallower zones floating plants 
develop. The open water on the north side is sheltered from the 
1 H. C. Cowles. “The Causes of Vegetative Cycles.” Bot. Gaz., 
Vol. 51, 1911, p. 171. 
