THE AMERICAN BOTANIST 



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Habits of Foreign Plants. — Most of the ordinary 

 weeds that are so common in gardens, along streets and in 

 vacant lots are foreign species that have become naturalized 

 in this country. Many of them have followed man for genera- 

 tions, and are just as intimately connected with him as the rat, 

 the mouse, or various kinds of insects. They have frequently 

 lost the habit of living with plants in natural surroundings, 

 and are completely dependent on the presence of man. Ac- 

 cordingly, such plants are uncommon in the woods, the prai- 

 ries, or elsewhere where the original vegetation has l^een un- 

 disturbed. They seem unable to compete with native vegeta- 

 tion or to make a place among native plants. On the other 

 hand most of our natives plants are soon killed by cultivation 

 or other disturbance of their environment, and consequently 

 do not persist as weeds. Our commonest garden weeds are 

 annuals and produce a large crop of seeds. Most of them 

 bloom during the late summer, when the garden plants are the 

 largest and cultivation the most difficult. Examination of an 

 ordinary vacant lot will usually show that forty to seventy 

 percent, of the plants are foreign, while a similar census of an 

 area of timber some distance from a dwelling will reveal less 

 than five percent, of naturalized plants. 



Botany Under a Tree. — On the campus of the Univer- 

 sity of Illinois stands a large austrian pine with branches close 

 to the ground. The men with the lawn mowers trim the grass 

 around the tree, but never try to get under the numerous 

 spreading branches. This makes a retreat where a number of 

 plants may grow which are not found elsewhere on the cam- 

 pus, and at the same time illustrates very well some interest- 

 ing features of the migration and colonization of plants. Every 

 year the wind blows thousands of seeds of many kinds of 

 plants across the campus, but only those which are fortunate 

 enough to stop in some such sheltered place as this ever have a 



