92 



OUTLINE OF PLANT GEOGRAPHY 



pine was dominant on gravelly and rocky soils, but also occurred 

 in the mixed forest. Where are good, well drained soils, bass- 

 wood, sugar maple, beech, elm, and canoe-birch are character- 

 istic trees, with which are associated white pine, hemlock, spruce 

 and balsam. The wetter areas may be swamps with a dense 

 growth of tamarack {Larix Americana) or white cedar {Thuja 

 occiderdalis). In the drier soils, about the southern margin of 





Fig. 18.- 



- American elm {Ulmus Americana), banks of Unadilla River, New York. 



Photo., E. L. Crandall. 



Lake Superior, the Norway pine (P. resinosa) is a common and 

 picturesque tree. 



In Michigan the mixed forest of the north passes into sandy 

 barrens in which the Jack-pine (P. Banksiana), predominates, 

 but there are also open groves of oaks, "oak openings," with 

 stretches of intervening grass-lands, or small prairies. The 

 latter formation is well shown in southwestern Michigan. 



The forest of southeastern Michigan is a deciduous one, made 

 up of much the same trees as that of New England. 



In the neighborhood of Detroit, in clay soils, the commonest 

 tree is probably the American elm; but sugar, silver, and red 

 maples, walnut, hickory, ash, and several oaks, are also char- 



