—43— 



The lists of both Cooper and Kauffman include two additional bryophytes 

 which have not been collected in the region covered by the present investigation, 

 namely Bryum intermedium (Ludw.) Brid. and Stereodon curvifolius (Hedw.) 

 E. G. Britton; while both Conklin and Kauffman list Jungermannia lanceolata 

 L. and Porella platyphylla (L.) Lindb 1 . To these should be added, as not elsewhere 

 recorded for Michigan, Anacamptodon splachnoides (Froel.) Brid. and Elodium 

 paludosum (Sull.) Loeske, collected by the writer at Lakeside, Berrien County, 

 in 1910. 



Of the 261 species to be noted in the present paper as occurring in the Doug- 

 las Lake region, no less than 101 appear not to have been previously reported from 

 the state. These species will be marked with a star (*). 



For a country of moderately rolling topography with little rugged relief, 

 a country of sands and gravels with almost no outcrops of bed rock (except at 

 Mackinac Island), a country which has been almost completely lumbered and 

 more or less extensively burned over, the comparative richness in species of the 

 bryophyte flora in the Douglas Lake region, at first thought, seems almost in- 

 credible. But this diversity is at once explained by the surprising variety of 

 habitats which this region, superficially so lacking in promise, reveals upon 

 closer examination. The principal types of habitat, in so far as these are of 

 bryological importance are as follows: 



The Hardwoods. — The magnificent forests of beech, sugar maple and hem- 

 lock which, with white pine, formerly covered the uplands throughout this region 

 are now represented only by occasional primeval stands and by somewhat -more 

 frequent second-growth tracts of woodland. 



The Aspens. — The prevailing type of vegetation on uplands today is dry open 

 woodland, more or less densely populated by aspen, with a sprinkling of other 

 ;rees. 



The Lake Bluffs. — Steep embankments, usually of gravel and from three or 

 four to more than fifty feet high, border the shores of Douglas and Burt Lakes 

 in several localities, affording conditions favorable to many bryophytes which 

 are found in no other type of habitat. 



Sandy Lake Shores. — Sandy lake shores in general possess little of bry- 

 ological interest. Certain species, however, appear to be restricted to the beaches, 

 growing at about the level of winter high water mark, but for the most part only 

 in places where the ground remains quite moist, even in summer. 



Rocks and Cliffs. — Through most of this region the only rock substrata 

 are afforded by the scattered to locally abundant glacial boulders; but Mackinac 

 Island abounds in rocks and cliffs, here as elsewhere mainly limestone. 



The Gorge. — One of the most striking physiographic features of the region 



'The majority of American specimens formerly referred to P. platyphylla, however, are now 

 assigned to P. platypyhlloidea (Schwein.) Lindb., and only one apparently authentic Michigan 

 record for the true P. platyphylla is known, viz., a specimen colbcted at Ann Arbor in 1907 by Dr. 

 Conklin. 



