THE LEAF. 



221 



c. From Scattered (Spiral) to Opposite-decussate. — 

 This phenomenon of bipartition of the leaf also occurs 

 in plants with alternate phyllotaxis, as in the oak, elm, 

 and rose, but it would appear to be less common in 

 these. In a weeping variety of Ulmus glabra shoots 

 for several nodes in succession bore leaves which were 



Fig. 58. — Stachys maritima. Shoot showing origin of scattered (spiral) 

 phyllotaxis by fusion of the two leaves at each node. (After Clos.) 



completely forked into two distinct leaves, although 

 occasionally a partially forked leaf also occurred ; when 

 two distinct leaves thus occurred side by side at one 

 node each bore a bud in its axil ; if the forking was 

 incomplete only a single axillary bud was present 

 (fig. 59). On other shoots such nodes in the forking 

 leaves were few and far between. In many of the 

 above cases the change in leaf arrangement does not 

 result in vertical displacement of the leaves, but in the 



