12 



Minnesota Plant Life. 



plants will be found, consisting among others of certain sand- 

 loving grasses, cockleburrs, pinks and fumitories, and clearly 

 distinct from the plants farther back upon the shore. Nor will 

 these plants develop so vigorously under any other conditions. 

 Again in the swamp region of the north, where a peat-bog is 

 slowly filling with moss and encroaching upon the forest, beau- 

 tiful illustrations of this zonal arrangement can be observed 

 with the tamarack and spruce trees becoming gradually smaller 

 and smaller toward the center of the bog. In meadows, too, 



FIG. 5. Zones of aquatic vegetation. In the center pond-lilies; at the edge smartweed; far- 

 ther back cat-tails, blue flags, sweet flags, and sedges; still farther back soft turf with 

 grass, moss, sedge and milkweed. After photograph by Williams. 



formed by the drying-up of lakes, are sometimes found en- 

 croachments of the meadow plants upon such knolls as were 

 originally islands surrounded by water. The meadow, as it 

 were, washes up upon the knoll and upon the banks of the old 

 lake, so that mingled with the dogwoods, willows and other 

 shrubs of the knoll or bank one will observe the grasses and 

 sedges of the meadow. 



Zonal distribution is a characteristic arrangement not only of 

 land, but also of water plants, and as one pushes his canoe from 

 the shore of a Minnesota lake he will doubtless find that he 



