THE COLOURS OF FLOWERS. 



treatise ; and our object must be to determine, not 

 why they are all as a group brightly coloured, but 

 why this, that, or the other particular blossom should 

 possess this, that, or the other particular hue. Why 

 is the buttercup yellow, while the stitchwort is white, 

 the dog-rose pink, and the harebell blue ? Why is 

 the purple foxglove dappled inside with lurid red spots ? 

 Why are the central florets of the daisy yellow, while 

 the ray-florets are pinky-white ? Why does sky-blue 

 prevail amongst all the veronicas, while yellow pre- 

 dominates in the St. John's worts, and white in the 

 umbellates ? These are the sort of questions which we 

 must endeavour briefly to answer, by the light of 

 modern evolutionary biology, from the point of view 

 of the function which each colour specially subserves 

 in the economy of the particular plant which 

 displays it. 



The brilliant pigments of flowers usually reside in 

 the specialised organs known as petals, though they 

 are sometimes also found in the sepals and bracts, or 

 more rarely in the stamens and even in the pistil. 

 For the sake of those readers who happen to be 

 imperfectly acquainted with the subject at large (and 

 also to bring the botanical reader definitely into the 

 required point of view), it may be well to begin with 

 a very brief description of the organs which go to 

 make up a typical flower, together with a short 

 account of the part played by colour in general in 

 the fertilising function. 



The essential elements in the flower are not at all 

 the showy and brilliant leaves which we usually 

 associate most with the name, but a set of compara- 

 tively small and unnoticeable organs occupying the 



