which belong to the flora of the lower Mississippi Valley, several of which will 

 be found noticed in the catalogue. The number of these is, however, relatively 

 small ; and the peculiar aspect of the flora of this district, as contrasted with 

 those already noticed, is given by the abundance of species \|hich are found, 

 though perhaps rarely, as far north as the centre of the State. Of these the forest 

 trees which alone attract the attention of others than botanists, will suffice for 

 examples. Some of these have already been enumerated, and to them may be 

 added the persimmon, the coffee tree, and the red bud, which, though conspicuous 

 objects in the flora of this region, are unknown in the northern part of this State. 

 x * x ****** 



The sources from which the accompanying catalogue was compiled, are as fol- 

 lows : 



A catalogue of the Plants of Franklin county, by W. S. Sullivant. 



A catalogue of the Plants of Fairfield county, by Drs. Bigelow and Hor. 



A catalogue of the Plants of Cincinnati, by Thomas G. Lee. 



A catalogue of the Plants of Cincinnati, by Joseph Clark. 



A Synopsis of the Flora of the Westsrn States, by Prof. J. L. Riddell. 



Manuscript catalogues of the Plants in Summit and Cuyahoga counties, by the 

 writer. 



I am also indebted to Dr. KelWor, f Cincinnati and Dr. Canfield, now of 



DO' 



Monterey, California, for valuable information in reference to the plants of Geauga 

 and Lorain counties. The brief sketch of the geographical botany of the State 



proposed for the origin of prairies, viz: that of Prof. Whitney, that they are due to a peculiar 

 fineness of soil ; or that of M. Lesquereux, that they are the beds of ancient lakes ; that of M. 

 Desor, that they are the lower and level reaches of sea bottom ; or, finally, that which attributes 

 them to annual fires, are alike wholly inapplicable. 



3d. The prairies bordering on, or east of the Mississippi, may be, and doubtless are, partly } 

 or locally due to one or more ef the conditions suggested in the above theories; but even here 

 the great controlling influence has been the supply of water. The structure of the soil of the 

 prairies coinciding with the extremes of want and supply of rain characteristic of the climate, 

 have made them now too wet and now too dry for the healthy growth of' trees. A sandy, 

 gravelly or rocky soil and sub soil, more thoroughly saturated with moisture, and more deeply 

 penetrated by the roots of forest trees, afford them a constant supply of the fluid which to them 

 is vital. This, as it seems to the writer, is the reason why the knolls and ridges composed of 

 coarser materials are covered with trees, while the lower levels, with finer sou, are prairies. 

 "Where greater variation of level exist, the highlands are frequently covered with trees, in virtue 

 of the greater precipitation of moisture which they enjoy. J. S. N". 



