168 IOWA ACAUEMV OF SCIENCES. 



INLAND GROUP. 



1. RIVER SERIES. 



1, The Missoui-i Flood pi a in. -At is not necessary in this 

 connection to discuss the early liistory of the formation of 

 this flood plain* as this follows the same general laws so 

 well set forth by Cowles. 



This is the youngest of the series, and near the shore of 

 the river is subject to frequent changes. The broad level 

 plain is from eight to twelve miles wide, varying but little 

 in the consistency of the soil or the vegetation from 

 Council Bluffs to Sioux City. Sparsely timbered except 

 near the shore lines of older streams, the bayous of 

 more recent formation or near the basis of the bluffs. In 

 the earlier stages of the development of this flood plain as 

 it exists today. The plants are mainly hydrophytic. 

 Among the lower plants, AS'/'/ror////7/ and Z/jfjueu/a. Of the 

 flowering plants: 



Potamos:;eto7i natavs. Xi^vitia major. 



Ranunculus intiUihctus . Utticulaf ia vuls^aris. 



Scirpus lacustris. Sciipus palustris. 

 Rumex verticillatus. 



SWAMPS. 



Owing to the wide flood plain the waters of the Missouri 

 have never had a very rapid current. It has frequently 

 shifted its course. When sufficient age has been obtained 

 mesophytic plants appear. One of the most conspicuous 

 of these is the PJwlaris arnndinacea, one of the vernal 

 grasses, which blooms and produces ripe fruit before the 

 dry season. During its early growth it is of hydrophytic 

 habit. It is thus semi-mesophytic. Banunciihis multifidus 

 is also a frequent inhabitant of these slow running streams, 

 and during its early existence only produces finely dis- 

 sected leaves freely floating in the water, but as the stream 

 dries up the plants at once develop smaller round, reni- 

 form, coarsely dissected leaves. These plants root in the 

 mud. 



♦ 1. C. 98. 



