294 OHIO BIOLOGICAL SURVEY 



very large and ever-increasing proportion of the area is growing up 

 into thickets very similar to the natural Sumac Thicket which, like the 

 Riverbank association, may be said therefore to have greatly extended 

 its boundaries since the advent of man. These Old Field associations 

 are not, however, altogether similar to the natural societies, but show 

 a considerable admixture of species not found in them. 



The Old Field Associations. It has already been remarked that 

 the uplands ]"e(|uire very careful handling to prevent washing and 

 wasting of the scanty soil. Thousands of acres throughout the region 

 have thus gotten away from their owners and become worthless for 

 agricultural purposes. In these lands and other worn-out fields there 

 has developed a somewhat definite association which covers a larger 

 portion of area than any of the natural associations. In many respects 

 it resembles markedly the Sumac Thicket just described, but its soil, 

 though very poor, is not so closely underlain with hard rock, and so 

 permits the growth of numerous species which do not find a place in 

 the natural thicket. 



The first plants that come into such fields, often appearing in 

 numbers before abandonment, are Andropogon scoparius and A. vir- 

 GiNicus, which sometimes occupy the ground almost to the exclusion of 

 other species. 



After them, or in pastured land instead of them, appear various 

 weedy plants, among which are : 



Ascyron hypericokles Honstoiiia JongifoVm 



Gnaphalium decurrens Hedeoma pulegreoides 



Meibomia canescens Meihomia obtiisa 



Potentilla canadensis 



Next come in the mountain sumac, Rhus copalijna, together with 

 the following plants completing the association : 



Riibus procumbens (Dewberry) Solidago nemoraUs 



Lespedesa hirta Etihtifi aJk<j]iicnsi.<< ( Highbush B.B.) 



Corylus americana Hypericum prolificum 



Malus glaucescens Titytlimalopsls corallata 



Smilax glauca Solidago juncea 



Ibidium gracilis 



After these plants have fully occupied the territory, reforestation 

 begins by the appearance of some of the arborescent species, among 

 which the first comers are often the Sassafras and the Persimmon 

 (Diospyros), together with the pines, P. rigida and P. virginiana; 

 which finally take possession to the exclusion of other trees. 



