Minnesota Plant Life. 2 i 



fruits and the fruits of a great variety of dandelion-like and sun- 

 flower-like plants. Sometimes the whole plant is distributed 

 by the wind and examples of this are especially striking upon 

 the prairie where the wind has free sweep. Thus, tumbling 

 plants like the Russian thistle, the tumbling mustard and the 

 tumbling grass, when their fruits are ripe separate all or the 

 greater part of the stem from its attachment and curve their 

 branches so that the whole takes the shape of a ball rolling 

 freely for miles over the level prairies before the wind. Some- 

 times the wind acts indirectly in the distribution of plants, as 

 for instance, when a portion of the boggy shore of some lake 

 breaks loose and is blown away to be anchored possibly under 

 new conditions across the lake. 



Water currents. Though the agency of currents of water 

 in transporting seeds is scarcely so universally employed as that 

 of the wind, it should not be overlooked. This agency is par- 

 ticularly important for heavy-seeded plants as their seeds are 

 often borne along a stream in its currents and eddies to find a 

 lodgment possibly miles below the point where they were intro- 

 duced. Other seeds, to facilitate their floating, are provided 

 with buoyant apparatus which adapts them also for wind distri- 

 bution. 



Man. One very important agent in plant distribution re- 

 mains to be considered, namely, man. Unlike the birds and 

 animals, man in his migrations is not so strongly regulated by 

 the changing rhythm of the seasons. On the contrary the prin- 

 cipal lines of migration of men since the advent of Caucasians 

 upon the continent have been from east to west, rather than 

 from north to south. Roads and trails have been beaten across 

 the plains and through the forests; railway lines have been 

 built, binding distant portions of the country together, and to 

 connect with them steamships cross the seas. Freights are car- 

 ried from one hemisphere to another, and along with that for 

 which there are invoices and bills of lading comes often a con- 

 signment of seeds of fruits, unrecorded yet none the less im- 

 portant. In this manner some harmful weeds as well as some 

 useful forage-plants have reached the fields of Minnesota. With 

 the immigration of men and women from Russia has come the 

 Russian thistle ; from France and England the cockles of the 



