[Vor. 8 
350 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
from east to west about 32 miles, the area being 632 square 
miles. The center of the county is approximately in latitude 
37°10’ north, and longitude 94°20’ west of Greenwich. The 
elevation ranges from about 825 feet in the valley of Spring 
River near the western boundary to about 1175 feet on the 
highest hills in the southeastern part. 
Topographieally, the area is a dissected plain, with hills of 
low elevation, situated on the western slope of the Ozark 
dome. Most of the country may be described as an upland 
prairie with considerable broken, hilly ground bordering the 
streams, especially along Center Creek in the southern por- 
tion. Through this plateau the larger streams have carved 
valleys of varying widths, in the alluvial plains of which 
they meander from bluff to bluff. These valleys, originally 
heavily wooded with deciduous forests of oak, maple, ash, 
walnut and many other trees, are now nearly all cleared and 
under agriculture. Remnants of the low forests remain only 
here and there, but considerable areas of the rocky, broken 
uplands in the southern part are still covered with a virgin or 
second growth of somewhat stunted timber, in which oaks and 
hickories predominate. 
The drainage system is simple, consisting of Spring River 
and its tributaries, flowing in the main from east to west. 
The most important of these are North Fork and Dry Fork 
on the north, and, to the south, Center Creek with its afflu- 
ents—Jenkins Creek, Jones Creek, and Grove Creek—and 
Turkey Creek, which flows directly into Spring River a little 
beyond the Kansas boundary. Spring River and the creeks 
to the south are perennial streams fed by many springs. 
North Fork and Dry Fork are intermittent but flow through- 
out the greater portion of the year. There are no large lakes 
or other natural bodies of water, but a few bayous or old 
channels along Spring River and Center Creek afford a habi- 
tat for some aquatic plants. 
With the exception of the alluvial valleys the soil is largely 
residual, resulting from the decomposition of the underlying 
rocks. In consequence, there is a rather close correlation be- 
tween the geology and local plant distribution. 
