202 ROUND THE YEAR 



trivance explains only a small part of the facility with 

 which weeds spread in cultivated ground. 



Canon Ellacombe in his pleasant little book on a 

 Gloucestershire garden observes that every year there 

 must be millions of seeds formed, and for the most 

 part ripened, in that acre or two, yet few of them 

 produce seedlings, while Groundsel, Thistle, and other 

 weeds seem to have an unbounded power of germina- 

 tion. Yet the garden flowers have their special con- 

 trivances too, less familiar to us than those of our 

 common weeds, partly because the exotic species are 

 less frequent here, and partly because they are not at 

 home with us. It often happens that an imported 

 plant cannot bring its contrivances into action for 

 want of a particular friendly Insect or some other 

 favouring circumstance, which the land of adoption 

 does not supply. Climate and soil may be adverse to 

 imported species. Some of our garden plants come 

 from countries which are much hotter or colder, much 

 drier or wetter than Britain. It is to be expected that 

 in all these matters the natives will be at an advantage 

 in comparison with forced immigrants. 



If this were all, if it were merely a question of 

 climate and soil, or of accustomed surroundings, all 

 plants might be expected to suffer when transported 

 to distant continents. But when we look into the 

 facts, we find that this is not at all universally the 

 case. The weeds of Europe do not suffer when 

 transported to the southern hemisphere, but flourish 

 and often drive out the native plants. The weeds of 

 the southern hemisphere are unable, however, to make 

 things even by invading any patch of ground 



