32 
r’rom shore. Gently sloping sandy shores that are subject to considerable 
wave action and the undercutting of the actual banks have a scant vege- 
tation of which Potamogeton filiform, is var. borealis is the commonest 
species. It is sometimes associated, in relatively quiet water, with a turf 
of Najas flexilis and a scattering of Myriophyllum exalbescens, Chara sp., 
Nymphozanthus variegatus , Potamogeton Richardsonii, and P. zosteri- 
f or mis. 
Emergent aquatics on relatively steep shores are usually bulrushes 
Scirpus validus, At Moose lake they are found in water 5 or 6 feet deep, 
growing alone or with Potamogeton pectinatus. They are very seldom at 
the water-line, on this or any other type of shore, but occupy a compara- 
tively narrow band a few yards away from the land (Figure 3, A, F, G, I). 
Shallow lakes often have other associations outside the bulrushes (Figure 
3, G, I). The cow-lily Nymphozanthus variegatus grows abundantly in 
many such situations. It may be alone or associated with pond weeds: 
Potamogeton praelongus, P. Richardsonii, and P. zosteriformis, water-mil- 
foil Myriophyllum exalbescens, bladderwort Utricularia vulgaris , spike- 
rush Eleocharis palustris, an abundant plankton, and the Chara of the 
bottom. These secondary species are not evenly distributed, but are very 
common in patches. The zone of lilies is constant on most of the marshy 
shores of Moose lake where it is 100 feet wide or more over long distances. 
The most extended marshy shores (Figure 3, I) have still another asso- 
ciation which involves the meadow sedge Carex trichocarpa var. aristata, 
and the tall marsh grass Fluminia festucacea. These species grow in 
nearly pure stands in water 3 to 4 feet deep, and were fruiting abundantly 
during the second and third weeks in August. It is of note that they are 
primary species in the flood-plain sloughs and delta lands along the main 
rivers. On the shores of upland lakes, however, they do not play a part 
in the adjacent meadow vegetation as they do in the lowlands. On a few 
marshy shores Equisetum limosum takes the place of Scirpus. 
When the bulrush zone occurs in shallow water it serves as a place of 
accumulation for a number of other species: bladderwort Utricularia. vul- 
garis, U. minor, pond weeds such as Potamogeton Richardsonii, P. zosteri- 
formis, P. Friesii, P. pmillus, water-milfoil Myriophyllum exalbescens , 
bur-reed Sparganium sp. (floating seedling), floating mosses Hypnum spp., 
and abundant plankton. The part taken by the off-shore Scirpus association 
in the formation of the characteristic peat ridges at the shores of lakes in 
Moose Lake basin has already 'been discussed by the writer (56) . When the 
general lake level is slightly lowered, as it has been frequently in rather re- 
cent times, these off-shore peat accumulations stand out as ridges at or near 
the shore-line, where their height and better drainage enable them to attain a 
mesophytic flora sooner than their surroundings (Figure 3, I) . Some lake 
shores show several of these ridges at intervals back from the water, indi- 
cating earlier changes in water-levels. In places the Scirpus association shuts 
off from the main lake a small narrow lagoon which when under water has a 
very open growth of Myriophyllum, Utricularia, and a few other species, but 
when exposed by drainage acquires a sedge marsh aspect. 
