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 V actinium, Arbutus, and Andro- 

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

 pinkish, or reddish. The highly developed Erica, 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 ccerulea is a 

 deep purplish blue. Monotropa alone, a very degraded 

 leafless saprophyte form, has greenish-yellow or pale 

 brown free petals. 



The Boraginacea are another very advanced family 

 of Corolliflorce, 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 (Anchusd), 

 the true bugloss (Lycopsis), the madwort (Asperugo], 

 and the familiar borage (Borago officinalis), used to 

 flavour claret-cup ; though all of them by reversion 



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