^98 



GEOGRAPHICAL DISTEIBUTION AND 



[Ch. XL. 



and wliicli have been received, perhaps, originally from Asia 

 alono- with them. Thus, together with the Barbary wheat, 

 the inhabitants of the south of Europe have sown, for many 

 ao-es, the plants of Algiers and Tunis. 



With 

 cottons of the East, or of Barbary, there are often brought 

 into France the grains of exotic plants, some of which 

 naturalise themselves. Of this I will cite a striking example. 

 There is, at the gate of Montpellier, a meadow set apart for 

 drying foreign wool, after it has heen tvashed. ' There hardly 

 passes a year without foreign plants being found naturaUsed 

 in this dryino--ground. I have gathered there Gentaurea 



' This 



iflora, Psoralea palwstina, and Hyp 



man 



fact is not only illustrative of the aid which 

 inadvertently to the propagation of plants, but it also demon- 



multipl 



animals 



same 



more common 



in seaports by the ballast of ships ; and several examples of 

 others which have spread through Europe from botanical 

 gardens, so as to have become 

 indigenous species. 



It is scarcely a century, says Linnseus, since the Canadian 

 Erigeron, or flea-bane, was brought from America to the 

 botanical garden at Paris ; and already the seeds have been 

 carried by the winds so that it is diffused over France, the 

 British Islands, Italy, Sicily, Holland, and Germany.* Several 

 others are mentioned by the Swedish naturalist, as having 



lY means. The common thorn-apple 



mil 



Willdenow 



noxious weed throughout all Europe, with the exception of 

 Sweden, Lapland, and Eussia. It came from the East Indies 

 and Abyssinia to us, and Avas thus universally spread by 

 certain quacks, who used its seeds as an emetic.f The same 

 plant is now abundant throughout the greater part of the 

 United States, along road-sides and about farm-yards. The 



Mimuhis 



* Essay on the Habitable Earth, 

 Amcen. Acad., vol. ii. ]). 409. 



t Principles of Botany, p. 389 



