4 WEEDS OF FARM LAND 



this country are chiefly cosmopolitan, and they either occur 

 naturally under arable cultivation in other countries or they 

 colonise rapidly if they are introduced. In parts of Australia 

 the bush has been cleared comparatively recently and the land 

 brought under cultivation. Where this has occurred the native 

 flora has disappeared entirely, being unable to put up with the 

 interference and the new conditions, but a weed flora has 

 appeared composed of species that are common as weeds 

 of cultivation in America and the Old World. The introduced 

 species have adopted their new home to such an extent that 

 they threaten to spread in a most injurious fashion, with the 

 result that legislation has been brought to bear, and many of 

 the more common species are proclaimed as noxious weeds. 

 Among the proclaimed plants of Victoria State there are 

 several that have been introduced from other parts of the 

 world, and that are even more obnoxious in Australia than 

 they are in this country, charlock, dodder, gorse, hemlock, and 

 several varieties of thistles, as the milk and creeping thistles, 

 being among the number. 



A similar thing has happened in Canada. The list of 

 Canadian Farm Weeds l consists chiefly of species that have 

 been introduced "from Europe, the native species being much 

 less in evidence. Wild oat, dock, sheep's sorrel, spurry, chick- 

 weed, corn cockle, buttercup, shepherd's purse, charlock, clover, 

 dodder, and ribgrass are but a few of the weeds that create as 

 much trouble in Canada as they do in England, although they 

 are not indigenous to that country but have been introduced in 

 the course of cultivation. The same story is told by collec- 

 tions of weed seeds that have been sent to Rothamsted from 

 Tasmania and the United States, and it is evident that certain 

 species are so indifferent to the wide variation of soil and 

 climate obtaining in different parts of the world that they will 

 colonise and spread anywhere under conditions of cultivation. 



From the early days of civilisation the weeds or alien plants 

 that spring up among cultivated crops have attracted much 

 attention because of the direct influence they exercise on the 

 food supply of mankind. Methods of eradication have 1 been 

 advocated and tested, and the problem considered from every 

 side, but in spite of all that has been done the weeds still 

 flourish and menace the well-being of the crops at every turn. 

 It is impossible to do away with weeds, for they are so well 

 equipped for holding their ground and reproducing their 



1 Clark, G. H., and Fletcher, J. (1909), " Farm Weeds of Canada ", 



