8 



The soil is calcareous, derived from the decomposition of the underlying rock, or 

 from the drift deposits, which are spread over a large part of it. the vegetation 

 is mingled, aborescent and herbaceous — forest and prairie. The forest trees are 

 mostly oaks — white, black, black-jack, laurel, burr, etc., with hickory, beech and 

 elm. The prairies appear first as lake-like openings in the forest, but near the 

 northwest corner of the State they occupy a large part of the surface, and with 

 their island-like clumps of timber, exhibit all the aspect of the prairies of the far 

 west. The farmers are both stock-raisers and grain-growers — the staple crops 

 corn and wheat, especially the former. The flora of this immense region, as 

 might be inferred, is of a mixed character, and even more than that of the other 

 districts I have noticed, refuses to submit to any narrow rules of classification. 

 It has, however, a peculiar facies, due to the relative abundance of the species 

 that compose it, and also to the presence of a number of the prairie plants of the 

 west, here on the eastern limits of their range.* 



The southern botanical district of Ohio, the region including the valleys of the 

 Ohio river and its tributaries, possesses no very tangible unity of character. Its 

 geological structure is exceedingly varied, as is its soil, the contour of the surface, 

 and, as a consequence its vegetation ; it may, however, be characterized as the 

 region of rich alluvial bottom lands now yielding year after year unequaled crops 

 of corn— the great staple of this district — but in the state of nature covered with 

 impenetrable jungles of Vernonia and Eupatorium, or with dense forests, to 

 which sycamore, black locust, black walnut, paw paw, etc., give an aspect quite 

 different from that of the wooded districts of the sections of the State we have 

 before considered. In the warm nooks of the valley of the Ohio, are many plants 



*The discussion of the question of the origin of prairies would here find an appropriate 

 place, but it is a subject not to be disposed of in a few words ; and the space which this article 

 already occupies, almost necessitates its exclusion. Since this catalogue was prepared, however, 

 the writer has spent a large part of several years on the prairies of nearly all parts of the con- 

 tinent where prairies exist. During this time, the question of the causes controlling the distri- 

 bution of arborescent and herbaceous vegetation received special attention ; and while he does 

 not flatter himself that he has fully succeeded in the analysis of these influences, he feels justi- 

 fied in reporting the following conclusions, to which he has been led by his observations : 



1st. The great controlling influence which has operated to exclude tree3 from so large a 

 portion of our territory west of the Mississippi is unquestionably a deficiency of precipitated 

 moisture. To this cause are due the prairies of Oregon, California, New Mexico, Utah, Nebras- 

 ka, Kansas, Arkansas and Texas. Throughout this great area, we find every variety of surface, 

 and toil of every shade of physical structure or chemical composition — unless in exceptional 

 circumstances, where it receives an unusual supply of moisture — if not utterly sterile, covered, 

 with a coating of grass. 



2d. To the great " plains," the typical prairies of the far west, the theories which have been 



