8 AMERICAN FERN JOURNAL 
THE PRAIRIE REGION 
The prairies lie immediately west of the Missouri 
river bluffs and in general cover the eastern half of the 
state, extending farther westward in the southern por- 
tion and are much restricted in the north central portion. 
These prairies with their gently undulating surfaces are 
the western representatives of those characteristic of 
Iowa and Illinois and are made up of indiscriminately 
arranged series of low rounded swells or hills inter- 
spersed with broad shallow depressions or limited valleys. 
The soil is of glacial drift which is quite deep in many 
places and is more or less veneered with loess. Drain- 
age systems are well established and ponds or lakes are 
infrequent or rare. 
This region is not conducive to fern growth. Where 
a belt of upland woods occurs Botrychium virginianum 
and Adiantum pedatum may be found. Onoclea sensiblis 
and Dryopteris thelypteris occur in wet prairie bottoms. 
Of the fern allies there are Equisetum arvense, preferring 
dry soil, and Equisetum laevigatum, preferring moist 
soil. Both species are frequent to common and widely 
distributed in this region. Equisetum variegatum is 
rarely found. In ponds Marsilea vestita occurs infre- 
quently or locally frequent. Isoetes melanopoda occurs 
rarely and locally. 
THE SANDHILL REGION 
The sandhills lie west of the prairies and cover much 
of the western half of the state, being confined largely 
to the central and west central portions. The eastern 
boundary of this region is not well marked, the prairies 
passing gradually into the sandhills, but in general the 
boundary line is irregular, receding westward in the | 
river valleys and extending eastward along the water 
sheds, the greatest eastern extension being in the north 
