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224 PRINCIPLES OF PLANT-TERATOLOGY. 



pocket which has a midrib of its own, and probably 

 represents an imperfectly-formed second leaf ; the leaf 

 most probably represents a fusion of two. Terminal 

 cup-shaped leaves have occurred in the garden gera- 

 nium (Pelargonium zonale, fig. 60). In some cases this 

 leaf congenitally arises in a perfectly terminal position 

 and there is no sign of any formation of the real apex ; 

 in other cases the leaf is not in the strictest sense 

 terminal, but makes a slight angle with the vertical, 

 and in this case, moreover, the displaced stem-apex 



Fig. 60. — Pelargonium zonale. Shoot bearing a terminal leaf in form 

 of an ascidinm which itself bears a secondary ascidium on its 

 lower surface, with (on left) diagrammatic longitudinal section of 

 base of terminal leaf showing displaced apex, tl, terminal leaf ; 

 ax sh, axillary shoot ; st, stem. 



can be seen in microscopic section in a lateral position 

 at the very base of the leaf with vascular bundles 

 passing out to it (fig. 60). The pitcher-leaf probably 

 occupies the position of both the terminal inflorescence 

 and the highest axillary vegetative shoot at the same 

 time. 



(2) Double Leaf. — In Buddleia Hemsleyana the upper- 

 most of the fully-matured pairs of certain branches of 

 a plant growing in Kew Gardens was represented by 

 a single structure composed of the two leaves (one of 

 which, in the case of one branch, was smaller than the 

 other) united by the midribs of their upper surfaces 

 for about two-thirds of their length from below 



