MacMillan: shores at lake of the woods. 1021 



collects in no special sink-holes. Under such topographic con- 

 ditions and adjustments of the environment, humus-banks, in 

 some cases, develop almost down to the water's edge. Any- 

 violent wave action would destroy them, but they may bear a 

 gradual rise and fall of level in the lake without becoming dis- 

 integrated. Upon such areas the true humus plants develop 

 abundantly. Certain special formations have been observed. 



I. Onoclea formation. Upon low humus banks the ostrich 

 fern is sometimes established as the dominant plant. This 

 happens on the shore of some small irregular islands in Moose 

 bay. As a back country formation, Onoclea beds are conspic- 

 uous on Garden island and elsewhere. The Onoclea beds on 

 humus shores have been observed covering areas of about 1500 

 square meters to the exclusion of other species. 



II. Pyrola formation. The little pipsewissa plants are the 

 dominant species but with them occur commonly Unifolium, 

 Gaultheria, Corallorhiza, Moneses, Goodyera, Gyrostachys and 

 many other small nitrophytes. 



III. Alnus formation. The alder sometimes occurs as a 

 dominant plant upon such humus banks. When thus established 

 its root-tubercles are very copiously developed. 



IV. Taxus formation. Upon humus shores of Garden 

 island, this conifer is a dominant plant upon certain stretches. 

 It occurs when the general back-country formation is conifer- 

 ous. 



V. Abies formation. The balsam marks a low humus shore 

 and by its prevalence indicates rather the drier typical humus 

 than the redistributed morassic humus such as Picea and Larix 

 seems to favor as a habitat. 



VI. Betula formation. Birch woods develop upon humus 

 stretches and in such cases maintain a vigorous growth with 

 an under-vegetation quite different from that formed when the 

 Betula establishes itself upon talus. In the latter case Epilob- 

 ium, Apocynums, Asters and other herbs not strongly nitro- 

 phytic are the subsidiary plants. In the humus formation 

 Lycopodium, Botrychium, Monotropa, Pyrola, Gircaea and nitro- 

 phytic lichens, fungi, and grasses of the genus Poa or Homalo- 

 cenclirus are abundant. 



Other formations no doubt arise in the Lake of the Woods 

 district, characterized by the dominance of other plants, but 

 those that have been denned will serve as indices of the eco- 

 logic conditions of humus shores. Such shores are quite azonal 

 in their distribution of plants, but the question of illumination 



