Prairie Flora 359 



Hackberry (Celtis occidentalis). 

 Ironwood (Ostrya virginiana).. 

 Willow (Salix amygdaloldes). 

 Red) cedar (Juniperus Virginiana). 



Along the borders of the forest may be found such shrubs as: 



Wild plum (Prunus americana). 



Wild red cherry (Prunus pennsylvanica). 



Choke cherry (Prunus virginiana). 



Sheepberry (Viburnum lentago). 



Downy arrow wood (Viburnum pubescens). 



Burning bush (Euonymus atropurpureus). 



Red osier dogwood (Cornus stolonifera, or more properly perhaps 

 stolonifera riparia of Rydberg). 



June berry (Amelanchier oblongifolia). 



Smooth rose (Rosa blanda). 



Hawthorne (Crataegus Sp.) 



Shining willow (Salix lucida). 



Heart leaved willow (Salix cordata). 



Sandbar willow (Salix longifolia). 



Buffalo berry (Shepherdia argentea). 



Wolf berry (Symphoricaipos occidentalis and S. orbiculatus). 



Nearly all of these shrubs and trees have an eastern range and 

 they appear to be advancing westward. The Buffalo berry is the only 

 one of them that seems to have come from the west, and that seems 

 only to be found at the head of Big tSone lake. Where the woodlands 

 are not heavily pastured the forest seems to be advancing on the 

 prairie. This advance is led by the shrubs, especially by the Wolf 

 berry. In small valleys and wherever the soil is uneven the Wolf 

 berry springs up, forming a dense shade, and destroys the tough 

 prairie sod. Under the shelter of its leaves sunflowers, silphiums and 

 other tall Compositae spring up, to be followed by box elders, green 

 ash, bur oaks and other forest trees. On low bottoms the sand bar 

 willow answers the same ends, forming dense patches on the river 

 bottoms to be followed by box elders, ash and elms. On other and 

 higher prairies the borders of the forest are extended through the 

 growth of shrubs, such as the wild rose, wahoo, choke cherries and 

 wild plums. As soon as the shrubs have taken possession of the 

 ground the seeds of trees spring up amongst them and the forest is 

 extended. 



The black walnut is found as far west as Walnut Grove in Cot- 

 tonwood county. There is a grove of sugar maples in what is known 

 as the Lynn woods on the headwaters of the Redwood river, where 

 it descends from the Coteau southwest of Marshall; and there is an- 

 other grove of the same tree where lake Whipple lies embosomed in 

 the Dovre moraine at Glenwood in Pope county. There is also said 

 to be a grove of sugar maples in the ravine formed by the Minnesota 

 river, where it cuts through the coteau in South Dakota. 



When we turn to the prairie flora of this region, we are beset 

 with many diflficulties. In the first place the prairie flora has been 

 destroyed. The breaking plow has been at work in this region for 

 about forty years, extending the wheat fields, and the remaining por- 

 tions of the prairie have been fenced in by barb wire fences and 



