108 IOWA ACADEMY OF SCIENCES. 



by three species {Ulnius Americana, U. racemosa and U. fulva). 

 Only one, the slippery elm, is abundant on the loess formation, 

 though Ulmus Americana is less restricted to low bottoms than 

 U. racemosa. Of the maples the sugar maple {Acer saccharinum) 

 is common on the loess, while the soft maple {Acer dasycarpum) 

 is exclusively a lowland species, so is box elder {Negundo- 

 aceroides). The mountain maple {Acer spicatum) occurs on the 

 loess. Tilia Americana is common on the loess formation. 

 Three cone bearing trees occur in northeastern Iowa {Abies 

 hahamea, Finns Strobus3,ud Juniperus Virginiana), but they occar 

 on other than loess soil. Of the ashes there are several species 

 the Fraxinus viridis delights in low bottoms. The F. Americana 

 occurs on higher soil. 



I cannot, in this connection, enumerate the shrubs that 

 occur, but they are numerous and may occur in thickets in 

 both loess and bottoms. Comparing the plants found in north- 

 eastern Iowa with those about La Crosse, Wis., where my 

 early botanical work was done, I may say that most of the 

 species occur and that the woody plants are more numerous. 

 Some of the southern species, however, fail to appear, bat in 

 places northern forms occur. The density of the timber 

 increases from the Mississippi east. In the drainage basin of the 

 Kickapoo Valley the finest timber in western Wisconsin occurs. 

 Nowhere have I seen such beautiful specimens of Acer saccha- 

 rinum, Tilia Americana and Quercus macrocarpa. This, too, is 

 outside of the loess region. In southwestern Minnesota, the 

 statement of McGee that there is a significant relation between 

 the loess sheeting and forest covering is very apparent. 



The most significant fact appearing to one who has made a 

 study of the loess flora of western Iowa is the absence of trees, 

 except an occasional cottonwood, en the peculiar mounds that 

 occur in parallel ridges along the Missouri river. These 

 peculiar hills rise abruptly from the rich, fertile Missouri bot- 

 tOQi and somewhat resemble the low foot hills of the Rocky 

 mountains. They are from 100 to 200 feet high. From a dis- 

 tance they look bare, but a day spent in this region will show 

 that the hills are full of botanical interest. I have made four 

 botanical trips at different times along the Missouri. On the 

 whole there is very little variation in the flora of Iowa. If we 

 leave out of consideration a number of most interesting plants 

 found in Winneshiek county by Mr. Holway and a few peculiar 

 southern plants found by Mr. Ferd Reppert, near the city of 



