CHAEACTEES OF THE LEAVES OE THE DATE PALM. 



15 



GROUP AND CLASS RECORD. 



Following the above comes the record of the classes and groups of 

 pinnae, made continuously from base to apex along one side of the 

 blade. The lower thorns, usually crowded, when not distinguishable 

 as to class or groups are indicated by a corresponding number of 

 straight marks, then 

 the groups are re- 

 corded by the compo- 

 nent initial letters 

 written together; for 

 instance, ar, ar, ar 

 would indicate three 

 successive groups, each 

 composed of one an- 

 trorse and one re- 

 trorse pinna. 



ANGLE RECORD OF THE 

 PINN.E. 



In order to accom- 

 plish the graphic rep- 

 resentation of the va- 

 rious angles formed by 

 the pinnae with the 

 axis and plane of the 

 blade, a diagram has 

 been prepared (form 

 B) 1 representing a 

 semicircular protrac- 

 tor as it might be ap- 

 plied for the reading 

 of the angles recorded 

 on form A. 



The first illustration 

 of the use of form B 

 (fig. 8) shows the pro- 

 tractor scale as though 

 laid flat upon the leaf, 

 the zero line AR drawn through its center being parallel with the 

 axis of the blade and zero toward the apex, the divergence of the 

 right and left ranks of pinnae would be indicated at 10°, 25°, 45°, etc. 



In the second illustration of the use of formB (fig. 9) the protractor 

 is placed as though cross-sectioning the rachis, the zero line PB coin- 

 ciding with the plane of the blade and the line of 90° bisecting the 



Fig. 8. — Diagrams showing the characteristic divergence of the pinnae 

 of a Deglet Noor date leaf, at 2 to 3 feet from the base of the leaf, 

 recorded on form B. The upper diagram shows the divergence 

 from the blade plane; the lower, the divergence from the apex: 

 A, An trorse pinnae; I, introrse; .R,retrorse. 



i Form B, reduced in size, is shown in figures 8, 9, and 10. 



