38 ECOLOGICAL RELATIONS OF THE FLORA. 



to be the factor whicli was eliminating the Potamogeton association 

 and fa^;^oring the spread of the hly pads. 



Helophytes — Sivamp Formations. 



This class of formations except for the sand type includes the greater 

 part of the Point, for the amount of land that is upland is much less 

 than that which is low and water-soaked. On account of the recent 

 formation of the Point, and the fact that new lagoons are being formed 

 by the great storms, etc., as explained by Ruthven, almost a com- 

 plete series of formations can be described. (Plate II b.) Thus we 

 have the amphibious formation (reed-swamp formation) composed 

 of many associations, the bush-swamp and the wooded-swamp 

 formations. 



Amphibious Formation — Car ex, J uncus and Scirpus Associations: 

 These associations appeared along the lagoons. The lagoon stucUed, 

 Long Lake (Plate XII a), was surrounded by jack pine ridges and was 

 itself being filled to a considerable extent by wind-blown sand as well 

 as by inwash and vegetable debris near the shore. This physiographic 

 feature was somewhat intermediate between the open water of the 

 bay and the half filled marsh, hence the vegetation consisted of the 

 formations found in each. In the open, shallow water the water-hly 

 association and the Chara persisted while extending from the shores- 

 the Scirpus, Juncus and Carex associations pressed out in the order 

 named. 



Along the shore of the lake the strip of helophytes was gradually 

 being narrowed by the encroachment of the xerophytes from the bank. 

 (Plate XII b). In places this encroachment was great enough to entirely 

 suppress the shrub zone of willow, dogwood and alder. This was 

 especially true on the side of the lake nearest the open bay. 



The Scirpus and Juncus associations were almost pure and found 

 growing in the water. The Carex association was a closed one, growing 

 on the banks where the ground was wet and soggy, yet offered solid 

 foothold (Plate XIII a). Here the greatest variety of plants was. 

 found as shown by the lists. 



Detail of the Carex Association. 

 Dominant Species: 



Carex filiformis. 

 Sub-Dominant Species: 

 Equisetum sylvaticum. 

 Alisma plantogo-aquatica. 

 Sagittaria latifoHa. 

 Phragmites conimunis. 



