458 



Minnesota Plant Life. 



of rushes and reed-grasses. Here, too, should be included the 

 beds of cat-tails, of blue flags, of arrowheads, burweeds, callas, 

 sweet-flags and sedges. In such regions a variety of accessory 

 plants habitually develop, such as the swamp butterweed, the 

 buck-bean, the swamp-docks and several members of the pars- 

 ley family. These plants often arrange themselves in zones 

 dependent upon the relative moisture of the soil, or upon the 

 depth of the water that covers the rootstocks and roots. Thus, 

 along the borders of Minnesota lakes, bulrushes generally grow 



FIG. 227. A marsh-loving sedge, showing fruit clusters. After photograph by Hibbard. 



outside of reed-grasses, and reed-grasses outside of sedges, 

 showing the exact adaptations of these kinds of plants to the 

 moisture-content of the soil and to the water covering their un- 

 derground portions. Most of the plants in reed swamps are 

 provided with rootstocks by means of which they propagate. 

 The strong rootstocks of bulrushes and cat-tails may serve as 

 examples. While pushing a boat through a bed of bulrushes a 

 careful observer will notice that the rushes stand in rows, and 

 these rows designate the position of the prostrate rootstock in 

 the bottom. From such branching rootstocks, common to 



