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A TEXTBOOK OF THEORETICAL BOTANY 



the pinnate leaf type with the phyllodic type (Fig. 983). The first leaves are 

 normally pinnate, with narrow petioles, but in subsequent leaves the petiole 



APEX 



B 



GLAND 



AXILLARY 

 BUD 



PHYLLODE BASE 



Fig. 982. — Acacia sp. A, Diagram of structure of phyllode. 

 B, Transverse section of flat portion of phyllode showing the 

 double row of vascular bundles. C, Transverse section of 

 ph\llode base showing stipules and petiolar structure. 

 (After Boke.) 



is broadened and the pinnate lamina is reduced until a stage is reached at 

 which the petiole has assumed the mature phyllodic structure and the lamina 

 has disappeared or survives only as a small pointed tip to the phyllode. 



The phyllodes of Oxalis differ from those of Acacia only in that the former 

 are horizontally flattened while the latter are usually flattened vertically. 



Phyllodes, like most leaves, arise almost entirely in the tunica of the 

 apical stem meristem. At an early stage in the development of the rudiment 

 a superficial meristem appears over the adaxial surface, which is responsible 

 for the broadening of the structure. At the top of the phyllode is a minute 

 point which represents a rudimentary terminal leaflet, while at its base two 



