454 



Minnesota Plant Life. 



Several different classes exist, all of them characterized by the 

 development of the underground portions of the plant that 

 is, the roots or rootstock in moist soil, while the aerial por- 



FIG. 224. Marshy place at the edge of a wood. After photograph by Murdock. 



tions, especially the starch-making areas, are exposed to atmos- 

 pheric evaporation. Like the majority of aquatic plants, most 

 of the swamp plants are perennial. A great many of them 



