124 Flowers and their Pedigrees. 



Again, you may have observed that I said just 

 now the primitive ancestor of the goose-grass had five 

 petals. But the present united corolla has only four 

 lobes instead of five, and it is this arrangement, ap- 

 parently, which has gained for the whole tribe the 

 name of stellate. Now the tropical Rubiaceae, which 

 we saw reason to believe represent an earlier stage of 

 development than the goose-grass group, have usually 

 five lobes to the corolla ; and in this respect they 

 agree in the lump with the whole great class of dico- 

 tyledonous plants to which they belong. Therefore 

 we may fairly conclude that to have four lobes instead 

 of five is a mark of further specialisation in the 

 stellates ; in other words, it is they that have lost a 

 lobe, not the other madder-worts that have added 

 one. This, then, gives us a further test of relative 

 development — or perhaps we ought rather to say of 

 relative degeneration — among the stellate tribe. Wild 

 madder, whose flowers are comparatively large, has 

 usually five lobes. Yellow crosswort has most of its 

 blossoms four-lobed, interspersed with a few five-lobed 

 specimens. Goose-grass occasionally produces large 

 five-lobed flowers, but has normally only four lobes. 

 The still smaller skulking species have almost inva- 

 riably four only. In fact, the suppression of one 

 original petal seems to be due to the general dwarfing 



