NOTES ON DIPTEROCARPS. 



47 



more simple equal cotyledons and the first two leaves are equal. 

 Shorea cotyledons are sagittately bilobed, and the first leaves are 

 paired: but Anisoptera cotyledons are four ridged, and the first 



/>Qtr- 



Fips. 9 and 10. Two cases in which the leaves of the whorl diff red from 

 each other in very little. 



leaves are in a whorl of four. In both genera with the next leaf, the 

 alternate condition sets in which persists through life. 



There is no important difference in the microscopic structure 

 of the petiole of a leaf of the whorl and of the fifth leaf : both 

 in section about the middle exhibit (see fig. 11) a ring of 

 normal cortex enclosing a ring of sclerenchyma within which is 

 phloem and xyleim and an included bundle with the xylem towards 

 the face of the leaf as drawn. Associated with the largest xylem 

 vessels are resin ducts to the number of five. Close under the blade, 



Fig. 11. Petiole in transverse section. 

 Scler., sclerenchyma: and r. Canal, resin canal. 



H. A. Soc, No. 75, 1917. 



