THE SAND-FLORA OF IOWA 



By Bohumil Shimek 



A relatively small portion of Iowa is covered with sand, yet 

 there is a sufficient amount of it to offer opportunities for inter- 

 esting ecological investigations. The sand and gravel surfaces 

 are the least stable, and are often modified by the action of wind 

 and water, thus offering fresh surfaces for the study of plant 

 succession. In all probability, the changes which take place in 

 the flora of our sandy surfaces today are essentially the same as 

 those which occurred on the drift-surfaces after the recession of 

 the glacial ice ; but the floras of the latter have long ago reached 

 the climax stages of their development, and are subject only to 

 very slow changes. 



With reference to their origin, rather than their flora, our 

 sandy areas may be divided into five principal types : 



1 — Lacustrine beaches. — These are illustrated by the sandy 

 beaches at Terrace Park, along Emerson's Bay, and at the head 

 of West Okoboji lake; by the beaches on the south, east, and 

 north shores of Spirit lake, and the north shore of East Okoboji 

 lake ; by the east and northwest shores of Clear lake ; and by sand 

 beaches along some of our smaller lakes. These beaches usually 

 grade from a low, new part near the water's edge, to a higher, 

 older part now seldom, if ever, reached by the waves. The 

 former is subject to frequent changes through the action of the 

 waves in summer and ice-push in the winter, and is usually de- 

 void of vegetation near the water's edge, as illustrated in Plate 

 I, fig. 1.^ It sometimes grades off into swamps, as on the north 

 shore of Miller's Bay and of West Okoboji lake, but more fre- 

 quently it passes through higher beach surfaces to ordinary 

 prairie, as may be observed on the eastern shores of the northern 

 part of Spirit lake, at Orleans, and at the northern and southern 

 extremities of West Okoboji lake. 



1 See also "The Plant Geography of the Lake Okoboji Region," Bull. Lab. Nat. 

 Hist., S. U. I., vol. VII, no. 2, plate VI, fig. 1, and fig. 3. 



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