66 THE COLOURS OF FLOWERS 



Among the very regular Caryophyllacece^ the small, 

 open Alsinece are never spotted or variegated ; and 

 even in the more developed Silenece, with their tubular 

 calyces, only the highest British genus, DiantJiiis 

 (Fig. 24), ever has marks on its petals. 



In most regular flowers, the lines are mere intensi- 

 fications (or diminutions) of the general colouration 

 along the veins or ribs of the corolla ; and they 

 point towards the base or claw of the petal, where 

 the honey is usually secreted. But in irregular 

 flowers, we often get a higher modification of colour, 

 so that one region of the petal is yellow or white, while 

 another is pink or blue ; and these regions often run 

 transversely, not longitudinally. Such modifications 

 usually affect the most highly altered parts of the 

 irregular flower. 



The common wild pansy, Viola tricolor^ affords a 

 good example of complex variegation. Its flowers 

 are purple, white, or yellow ; or have these pigments 

 variously intermixed. The two upper pairs of petals 

 are usually the most coloured ; the lower one is 

 broadest, and generally yellow at the base, with dark 

 lines leading toward the spur. Viola palustris ex- 

 hibits the same tendency in a less degree ; it is pale 

 blue, with purple streaks. V. canina has hardly more 

 than a few darker or lighter lines. The whole family 

 is immensely interesting from the present point of 

 view, and should be closely observed by the student 

 at first hand. Its changes and varieties will be found 

 full of instructive suggestions as to the origin and 

 nature of colour modifications. 



InPolygala vulgaris,t\iQ two coloured petaloid sepals, 

 commonly called wings, are also delicately veined. 



