72 



BUDS AND STIPULES 



In other cases the leaves form successively a more 

 or less complete covering for those that follow, as, for 

 instance, in the St. John's Wort (Hypericum) (figs. 

 107, 108). 



In the Common Barberry (Berberis vulgaris) (fig. 



109) the primary leaves are changed into spines. 



The bud, however, in the axils of these spinose leaves 



A develops into a short axis with 



foliage leaves. This is why 



the leaves in this species are 



collected in tufts. 



In Azima tetracantha (a 

 member of the Salvadoracece, 

 a small tropical family of Di- 

 cotyledons) the axillary buds 

 are rather remarkable. What 

 3ak _ appear to be two spines situ- 



berry (Berberis vulgaris), a ted in the axil of the leaf 



showing three spines, Sp, 



representing the leaf. Nat. are really the first pair of 



A, s^m'; l. L, leaves on a lateral leaVeS f the axillary shoot, 

 shoot arising in the axil of the t_ it _ ,1_ -*-,-,# 1,^,-, ~~ 



spiniform eaf, and themselves In their early stages they are 



red uced to short, subulate spines ; , , ,. , ., 



i/, L',more perfect leaves on the erect, closely applied, and very 



same lateral shoot. 



short, but when fully developed 

 they become hard, spiny, and diverging. Their foliar 

 nature is further indicated by the fact that a slender 

 groove runs along the opposing faces from apex to 

 base, where there is a deeper cavity, as if a sheath 

 were attempted. They are also articulated with the 



