APRIL 67 



fixed nitrogen from the soil. That, at least, is the 

 suggestion from the peculiarity of rhododendrons 

 growing on limestone, pointing to the fungus being 

 unable to thrive in contact with lime, having transferred 

 itself to the foliage where it may function freely. 

 Similarly, the impatience of drought shown by rhodo- 

 dendrons may in reality arise from the failure of the 

 symbiotic fungus to survive severe desiccation. 



XVI 



A correspondent of one of the horticultural journals 

 recently (1920) asked for explanation of the The 

 preponderance of white and yellow in the colours of 

 blossoms of early flowering British herbs, 

 thereby touching the fringe of a subject which has 

 attracted research by many botanists, and contains a 

 problem far too profound to be considered at length in 

 these casual pages. Nevertheless it is one which must 

 often present itself to any one who gives more than 

 superficial attention to vegetation, and lovers of flowers 

 may care to note the main conclusion to which research 

 in this matter is tending. 



First, it may be remarked that the inquiry above 

 referred to was limited to the colours of early flowering 

 British herbs, in the flowers whereof he assumes that 

 white and yellow prevail over all other hues. But is 

 that assumption correct ? In a country like Great 

 Britain, which has been for so long extensively culti- 

 vated, the native flora has been much displaced and 

 expelled from many tracts where once it flourished. 



