1889- J BOTANICAL GAZETTE. I 27 



Notes on the flora of Iowa 



A. S. HITCHCOCK. 



Iowa can not boast of a flora remarkable for its diversity. 

 It contains no mountain ranges, no arid deserts, no sea coast, 

 extended lake shore or dreary swamp. It is essentially a 

 prairie state, but is not included in that vast and character- 

 istic region known as the "Great Plains." It lies on the 

 western border of what is known as the " Manual region." 

 Of the phienogamous plants recorded for Iowa (about 1,300 

 species and varieties), there are not more than forty that can 

 not be found in Gray's Manual. Part of these have been de- 

 scribed since the manual was written, and are found within 

 the geographical limits covered by this most excellent book. 

 Nearly all the remainder are to be found only in the extreme 

 western part of the state. 



Although there are no dense forests in the state, yet the 

 wooded flora is quite diverse. With the exception of coni- 

 fers, Iowa will compare favorably in this respect with other 

 states having more varied geological characters. 



Of the order Coniferae five species are recorded by Prof. 

 Arthur. I have seen but two, viz., Juniferns Virginiana L., 

 in the northern part of the state, and J. communis L M which 

 is quite common along the Iowa and Cedar rivers. 



The number of species of trees, as well as individuals, in- 

 creases as one goes south or east from the northwest corner 

 of the state. The oaks increase from three to thirteen. Pop- 

 ulus moniiifcra Ait. is replaced by P. grandidentaia Mx. and 

 P. tremuloides Mx. In the southern 'part are found gjicrcus 

 imbricaria Mx., Cercis Canadensis L., and Asimina triloba 

 Duval, which are more southern in their range; in the east- 

 ern part Dirca falustris L. and two species of birch, which 

 are eastern. 



The only portion of the state that shows any radical dif- 

 ference from the rest, as regards its flora, is the western bor- 

 der, the bluffs along the Missouri river. 



From Hamburg, in the southwestern part of Iowa, to 

 Sioux City, where the river leaves the Iowa line, we find the 

 bluffs extending like a miniature range of mountains, as seen 

 from the river, sometimes with the muddy Missouri flowin 

 at their base, and again several miles away. m m 



Aa tt ' thev are five miles back, but rise preapi- 



