PLANTS ALWAYS SPREADING 



Every species is always trying to colonize new ground, to 

 seek fresh fields and new pastures. Plants are not content 

 to keep to the old habitats, but every species tries to scatter 

 its pioneers over all the neighbouring country, so that, as 

 often happens, if it is exterminated or suppressed in one 

 locality, new generations luxuriate elsewhere. 



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