THE CLOVER FAMILY 



head of florets, that it was slowly lengthened 

 out and the flowers gradually made larger ? The 

 suggestion is reasonable enough, but it so happens 

 that the clovers possess other features, besides that 

 of their closely arranged heads of florets, which 

 tend to show that they are more evolved and of a 

 higher type than the other genera of their family. 



By pulling to pieces one of the larger pea- 

 flowers, such as broom or sweet pea, we shall find 

 that it possesses five coloured petals. A glance at 

 Fig. 65 (Plate 44) will show these. There is first a 

 large petal above, known as the ^' standard," and 

 below this is another pair termed the alae or 

 '' wings," and inside these still another pair (often 

 more or less united) designated the carina or 

 " keel." These same parts may also be readily 

 traced in one of the little blossoms of the clover ii 

 a magnif3nng lens is used when examining it. 

 There is, however, one important difference. The 

 clovers have joined together their petals at the 

 base to form a tube, at the bottom of which the 

 nectar is stored. 



Now I have previously pointed out (p. 10) when 

 dealing with the inflorescence of the wild camo- 

 mile and foxglove, that this joining together of 

 petals is a sure sign of advancement, because the 

 flower is then adapting its structure to the require- 

 ments of some particular insect visitors. Seeing 

 that this feature is, in the Pea-flower family, con- 

 spicuously developed only amongst the clovers, 

 there is good reason to suppose that they are more 

 highly evolved than genera with separate petals. 



153 



