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 somewhat 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 flora, 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 rather 
