BARBERRIES. 



601 



sess leaves which are obviously compound, the chief exception 

 being those eighty species (forming the subgenus Euberheris) 

 which in their leaves agree essentially with Berheris vulgaris. 

 In view of these facts, botanists have been led to adopt the some- 

 what paradoxical theory that leaves of the euberberis type are in 

 reality compound though unifoliolate. 



The question as to how such a curious state of things could 

 have come about is so closely connected with what concerns the 

 evolution of the other vegetative organs that we shall do well to 

 consider them all together. 



In attempting to reconstruct for ourselves the main features 

 of the original ancestral barberry we are much helped by the fact 

 that besides Berheris vulgaris, which is the only representative of 

 the genus in central Europe, there have been developed a mul- 

 titude of species in Asia and a still larger number in the two 

 Americas ; for it is clear that this must considerably increase the 

 chances of our being able to find something like the primitive 

 form persisting in certain living species. Guided by the principle 

 that evolution is for the most part attended by increase of differ- 



FiG. 6. 



6. BeEBERIS AQUIFOLItlM. 



FlQ. 7. 



Fio. 8. 



Fig. 6. Beeberis aquifoliiim. Quinquifoliolatc leaf. 

 Fig. Y. Berberis trifoliata. Trifoliolate leaf. 



Fig. 8. Berberis vulgaris. Unifoliolate leaf. A indicates the point of articulation of the 



leaflet. 



entiation, we may fairly assume that the branch system of the 

 prototype differed from Berheris vulgaris in having the inter- 

 nodes approximately equal, thus making the lateral branches on 

 the one hand and the main branches on the other more nearly 

 of a length and all the leaves uniformly disposed in elongated 

 spirals. 



Such a condition is indeed tolerably well exhibited in the ma- 

 honias, as may be seen in the " holly-leaved barberry " (Fig. 5), 



