202 IOWA ACADEMY OF SCIENCES. 



Armstrong Grove townships, and occasionally elsewhere in 

 the northern half of the county, are low ranges of morainic 

 hills, which tend some\yhat to relieve the otherwise mo- 

 notonous landscape. 



Drainage and cultivation are rapidly changing the 

 marshes and, in some cases, even the lakes, into pastures 

 and cultivable fields; and, therefore, the area once occupied 

 by a hydrophytic vegetation is being greatly diminished. 



There are comparatively few xerophytic plants in the 

 county, and these usually occupy favorable localities along 

 the river bluffs, or on the sterile, morainic hills. The flora 

 of the woods and prairies resembles more closely that of 

 the adjacent territory to the east and north; only a few 

 typical western plants coming within our borders. 



There are no rock exposures within our limits, and 

 therefore the soil is unsuited for many of the ferns and 

 other plants common to rocky woods. The forest area is 

 small, being confined to the banks of the lakes and streams, 

 but since the prairie fires have ceased, the wooded area 

 shows a tendency to increase. 



So large a proportion of the county consists of cultivable 

 or pasture land, that very many of the indigenous species 

 of plants must eventually become extinct within our area. 

 Some few, already, can no longer be found, and it is with 

 the view of recording the original fiora, that this paper is 

 prepared, as the author resided many years in the county 

 when nine-tenths of its surface was covered by the virgin 

 forest and prairie vegetation. 



Compared with the area, the number of plants listed is 

 small, only 590, including those introduced; but this may 

 be accounted for, partly at least, by the slight diversity in 

 surface and soil, and by the fact that it lies near the head- 

 waters of its drainage streams, and is thus less favored by 

 nature for seed distribution by natural agencies. 



The climate of the county, like that of all portions of 

 the northern Mississippi valley, is subject to great variation 

 in temperature, the annual variation occasionally being 

 as much as 140 degrees, the yearly mean being about 45 

 degrees. The annual precipitation, according to rathe 



