56 PLANT SUCCESSION AND CROP PRDDUCTION 



more northern species are known in the eastern than in the west- 

 em section of the state. The southern evergreen trees are Pinus 

 echinata, P. rigida, P. virginiana, and Jnniperus virginiana. In 

 addition should be mentioned the bear oak, Quercus ilicifolia, which 

 reaches the northern edge of its range in Ohio. There are also nu- 

 merous shrubs and herbaceous plants of the southern center which 

 reach the limit of their ranges. These perhaps belong more fairly 

 to the deciduous center and are simply its southern species, rather 

 than species of the southern center reaching up into the deciduous 

 center. The prairie center is rapidly disappearing and is being re- 

 placed largely by cultivated lands. The prairies if planted now 

 with trees would undoubtedly support the vegetation of the central 

 deciduous forest. The bogs and the prairies both belong in the gla- 

 ciated portion of the state and were most numerous in the western 

 part. One of the best evidences of the northward migration of 

 plants since glacial times is to be seen in the plants which were left 

 in the undrained depressions. They became established in early 

 post-glacial times, and the deposits of peat since have tended to 

 keep a cool substratum, which led to the preservation of these 

 species. 



E. The Crop Centers of Ohio 



The crop statistics of Ohio have been faithfully compiled by 

 the Ohio Board of Agriculture and published for its citizens. This 

 constitutes a valuable annual record which indicates the scope and 

 magnitude of one of Ohio's greatest businesses. These records have 

 been drawn upon freely in gathering the present data. The sta- 

 tistics are published by counties so that each community may see 

 what it is doing and what its neighbors are doing. For convenience, 

 the compilers have divided the state into four sections — northeast, 

 southeast, northwest, and southwest — and the county totals are 

 summed in accordance with this division. For our present purpose 

 this will not always show that crops center in a certain area. The 

 political divisions do not all correspond with natural physiographic 

 and geographic ones. The ivriter has not hesitated therefore to add 

 or substract county totals from one district where the geographic 

 data warrants, and place these in another group. Wherever this is 

 done attention is called to the fact that the names of the counties 

 specifically mentioned. This rearrangement of data is in accord with 

 the plan of the whole line of investigation here recorded, namely, 

 the genetic point of view, which aims to show the relation of the 



