22 Minnesota Plant Life. 



wheat ; from Italy some mustards ; indeed, from all the coun- 

 tries of Europe plants have found their \vay in company with 

 man. Some of them are later immigrants than others. Those 

 which crossed with the pilgrim fathers are now as much at home 

 as those to the manner born. Others, the advent of which 

 dates from yesterday, have not yet shown all their capal^lities, 

 and doubtless even now the dangerous new weeds of the next 

 decade are some of them precariously existing as little colonies 

 upon ballast-heaps or along the lines of eastern or western rail- 

 ways. 



Associations between migrating plants. When plants travel 

 they do not always travel alone, but in company as man does, 

 who when he migrates brings with him his horses, oxen, sheep, 

 fowls, dogs, and other domestic animals which have become 

 attached to him. So the plant when it migrates often takes 

 with it other plants. Thus where the maples go, there go also 

 those curious fungi that grow upon the leaves, looking like little 

 drops of tar. With the willow as it is uprooted and floats down 

 a stream, perhaps finding a foothold for its twigs somewhere 

 below, go the lichens and mosses upon its bark. 



There is something about the proximity of certain kinds of 

 plants which is very agreeable to other varieties, so that gen- 

 erally with ])inc trees one finds wintergreens associated, and 

 with peat-mosses, cranberries. The latter are not associations 

 like the associations lietween the maple and the fungus upon its 

 leaves, but are rather indications of kindred tastes in habita- 

 tions. The establishment of one kind of plant over an area 

 may be the natural and, perhaps, the necessary pre-requisite for 

 the development of another plant which has formed the habit 

 of attaching its fortunes to those of the first one in the field. 

 Plants, also, by their position and attitudes strongly influence 

 the distribution of other plants. If plants, which are accus- 

 tomed to (lcj)en(l upon winged seeds for their distribution, find 

 themselves gradually enclosed by the foliage of strong-growing 

 neighbors it will be diflicult, ])crliaps, for them to extend farther 

 the range oi their seeds. Or, possibly, the berries which were 

 attractixc during a season when neighboring plants were not in 

 fruit may not be so attr;uti\e another year when the adjacent 

 forms arc ri])ening their own larger, more highly colored, more 

 highly scented or sweeter fruit. 



