LAW OF PROGRESSIVE COLOURATION. 49 



so much so that, as we all have noticed a hundred 

 times over, they often colour whole tracts of hillside to- 

 gether. In all probability there are no really yellow 

 heaths. The bell-shaped blossoms mark at once the 

 position of the heaths with reference to insects ; and 

 the order, according to Mr. Bentham, supplies us 

 with more ornamental plants than any other in the 

 whole world. Among our British species, in the less 

 developed forms, like Vaccininm^ Arbutus, and Andro- 

 meda^ the flowers are usually white, flesh-coloured, 

 pinkish, or reddish. The highly developed Ericce, on 

 the other hand, are mostly purple or deep red. E. 

 vulgaris has the calyx as well as the corolla coloured 

 with a mauve variety of pink. Menziesia ccsrulea is a 

 deep purplish blue. Monotropa alone, a very degraded 

 leafless saprophyte form, has greenish-yellow or pale 

 brown free petals. 



The BoraginacecB are another very advanced family 

 of CorolliflorcB, and they are blue almost without 

 exception. They have usually highly - modified 

 flowers, with a tube below and spreading lobes above ; 

 in addition to which most of the species possess 

 remarkable and strongly-developed appendages to the 

 corolla, in the way of teeth, crowns, hairs, scales, 

 parapets or valves. Of the common British species 

 alone, the forget-me-nots {Myosotis) are clear sky- 

 blue with a yellow eye ; the viper's bugloss {Echium 

 vulgare) is at first reddish purple, and afterwards a 

 deep blue ; the lungwort {Pulmonaria officinalis) is 

 also dark blue ; and so are the two alkanets {Anchusa)^ 

 the true bugloss {Lycopsis)^ the mad wort {Asperugo), 

 and the familiar borage {Borago officinalis), used to 

 flavour claret-cup ; though all of them by reversion 



£ 



