﻿52 BOTANICAL GAZETTE TJANUAR^ 



assisted by the fact that a good portion of these northern town- 

 ships have a light surface soil, which seems unsuited for the hard 

 wood societies in the absence of humus. That the climatic fac- 

 tor is not the main one in this is shown by the existence of vast 

 reaches of typical maple and beech forest in the northern part 

 of the peninsula. 



The strongest point in favor of the idea just expressed is 

 found in the fact that at the time of settlement practically all of 

 societies T and II in the northern part of the county were well 

 mixed with pine. In some places the pine stumps are so numer- 

 ous as to raise the question whether the hardwood is not an entirely 

 recent development. It is probable, however, that scattered 

 maples and beeches were mingled with the pine, and that on the 

 removal of the latter their seedlings simply took possession of 

 the ground and shut out the pine seedlings. ^^ Also in societies 

 II and III, west of Rockford and as far south as Mill Creek, the 

 pine is still pronounced, and in many small spots society IV, or 

 even V, still retains its hold. As has been noted before, this is 

 a mixed group and is hard to classify. There are no traces of 

 pine in the hard wood forests to the southward. It may well be, 

 however, that a further extension of this study will show that 

 this hypothesis of the historic factor is utterly untenable. 



Another line of evidence seeming to throw some light upon 

 the historical development of this flora is that obtained from a 

 comparison of the several sand plains of the region. There is a 

 well marked sand plain just south of the boundary of Kent 

 county, which I have termed the Green Lake sand plain. The 

 soil here is like that of the higher part of the Grand Rapids 

 plain, very sandy, but with a good admixture and coating of 

 humus so that at the surface it appears loamy. The vegetation 

 is made up of all five of our societies. In general the type is 

 that of society III, but there are many spots, especially on the 



'3BeaI has shown that oaks, maples, etc., can reach a considerable age in dense 

 forests without any marked growth. An oak may thus be twenty-five years old and 

 yet have a height of only a few inches. If the shade-producing plants are removed 

 these dwarfed trees will set up a renewed growth. For figures of such dwarfed trees 

 see Beal, W. J., Observations on the succession of plants in northern Michigan. 

 Annual Report Mich. State Board of Agriculture 27: 74-78. 1888. 



