LA W OF PROGRESSIVE COLOURA TION. 35 



It is among the higher ranunculaceous plants, how- 

 ever, that we get the fullest and richest colouration. 

 Columbines (Aquilegia) are very specialised forms of 

 the buttercup type (Fig. 10). Both sepals and petals 



FIG. 10. Flower of columbine (.A quilegia vulgaris), with petals produced into 

 honey-bearing spurs ; purple or blue. 



are brightly coloured, while the former organs are pro- 

 duced above into long, bow-shaped spurs (Fig. 1 1), each 

 of which secretes a drop of honey. The carpels are also 



D 2 



