20 MASSACHUSETTS HORTICULTURAL SOCIETY. 



is that of Elodea canadensis, known in Europe as "water-pest." 

 At home, in America, this is an insignificant water-plant ordi- 

 narily overlooked except as it occurs in reservoirs. But a few- 

 plants, spreading from an aquarium to the River Cam in England, 

 soon clogged the stream, and from this and perhaps other similar 

 sources it has spread over England and much of continental 

 Europe, everywhere developing so vigorously as scarcely to 

 resemble the slender unassuming American plant from which it 

 sprung. In return, however, the European water-cress intro- 

 duced into Xew England brooks behaves with as little reserve, 

 and often the brooks of which it has taken possession become so 

 clogged by it as to cause serious damage. Another aquatic, the 

 water chestnut ( Trapa natatis), introduced some years ago as a 

 cuiiosity from Asia, was placed in the Concord River, where it 

 has become such a nuisance that it is necessary to weed it out of 

 the Sudbury River above its junction with the Assabet. 



Besides the methods of transportation from place to place 

 which we have already discussed, there is another which is at 

 present particularly instrumental in the rapid spread of weeds. 

 I refer to the railroad. Besides carrying freight and passengers, 

 the ordinary train transports uninvited the tine seeds of many 

 plants from one part of the country to another. No better 

 botanizing ground can be asked by the person interested in novel 

 weeds than the freight yards of a trunk railroad, especially if the 

 employees of the road have been negligent or thoughtless about 

 keeping down weeds. As in case of the plants of ballast lands 

 and of recently seeded ground many of the newly introduced 

 plants quickly perish; but others, with the slightest encourage- 

 ment, become permanent elements of the flora and take every 

 advantage of the railroad as a means of travel. The progress of 

 many bad weeds is readily traced to the railroads, and at the 

 present time roads entering New England from different direc- 

 tions are bringing to us as many different vagrants. In the late 

 TO's a coarse yellow-flowered plant, Senecio Jacobaea^ familiarly 

 known by the suggestive name " Stinking Willie," aj)peared as a 

 waif on ballast at some points along Northumberland Strait in 

 eastern New Brunswick and adjacent Nova Scotia. By 1884 

 it had begun to spread along the local railroads; and now it has 



