IOWA ACADEMY OP SCIENCES. 
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system. • The divide^ separating these two systems, passes 
southeasterly across the center of Union county, thence south- 
ward near the line of Decatur and Ringgold counties. Adams 
county rolls southwesterly and is drained by the Nodaway 
system, which system also drains the eastern portion of Mont- 
gomery and Page counties, the river system flexing from a 
southwesterly to a southerly direction, in the southeastern 
portion of Montgomery county. Taylor county has the Platt 
river system, and rolls to the southward. 
The western portion of Montgomery county is drained by the 
Nishnabotany system, which runs southwesterly, crossing the 
northeastern portion of Page county; thence bearing westward 
to Riverton, in Fremont county, where the different systems of 
the Nishnabotany unite into a single stream; the whole system 
lies east of the loess hills which border the Missouri river bot- 
toms. The river systems of the rectangle, in general, flow 
southwest, except in the extreme eastern portion, where they 
flow southeast. The whole county is cut into numerous north 
and south divides by the many tributaries of the Platt. 
Throughout this rectangle of six counties, the flora presents 
a complex nature, which is common throughout the region. 
The native flora is much restricted in extent, though it persists 
in many portions where the primeval sod has as yet been 
unfurrowed. The waysides, the narrow strips along the rail- 
way, and portions next the back settlements, still grow the 
original prairie grass and the accompanying flora, while many 
similar tracts are continuously pastured, and present little 
flora, except here and there a thicket. 
In this region the western flora is passing eastward and the 
eastern flora westward. Many species, on their tramps in 
opposite directions, seem to have met in this region, and 
established themselves, and to have become an integral part of 
the flora. Examples of the western forms are Lactuca 
'pulcliella D. C., Plantago aristata Mx., Solanum rostratum , 
Hordeum pusilluinfi Nutt., and many others as will be seen from 
the list. Among those moving westward are the Lepidiums, 
Brassica nigra Koch. , Capsella bursa-pastoris Moench. , XantJiium 
canadense Mill., Ambrosia artemiscefolia L., and A. trifida L., 
Antliemis cotula D. 0., Datura stramonium L. and D. tatula L , all 
of which are becoming conspicuous in the waste land through- 
out the region. The prairie portions yield Silphiums, Heli- 
anths, Liliums, Psoraleas, Anemones, Ceanothus, Asters, and 
