BULLETIN OF THE 



Contribution from the Bureau of Plant Industry, Wm. A. Taylor, Chief. 

 June 23, 1915. 



(PROFESSIONAL PAPER.) 



BOTANICAL CHARACTERS OF THE LEAVES OF THE DATE 

 PALM USED IN DISTINGUISHING CULTIVATED VARIETIES. 



By Silas C. Mason, 

 Arboriculturist, Crop Physiology and Breeding Investigations. 



CONTENTS. 



Page. 



Introduction 1 



The date tree 3 



Leaf characters of the date 3 



Use of the field protractor 13 



Forms for the observer's use 



Application of the system to the Deglet Noor 

 variety and its seedlings 



INTRODUCTION. 



At the present time most students of the date rely largely, if not 

 wholly, on the fruiting characters for means of distinguishing the 

 numerous varieties. 



While it is recognized that in the Old World date-growing countries 

 the natives distinguish almost intuitively the different varieties of 

 dates by the tree habit and leaf characters, but little attention has 

 been given to these points by European and American students of the 

 date and no attempt has been made to systematize these characters. 



The date trees certainly possess such characters, and the varietal 

 distinctions are as constant in the trunk and leaf as they are in the 

 fruits. 



From the beginning of the study of the imported date trees in the 

 American gardens there has been felt the need of a method of com- 

 paring and describing the different trees in the absence of their fruit 

 and independently of their fruit characters. 



This becomes of importance in assisting date work along two very 

 distinct lines — the identification and comparison of varieties, either 

 imported or originating in this country, and the study of seedlings 

 originating from the cross-pollination of different varieties. 



Note. — This bulletin is of interest to date growers, especially in the Southwestern States. 

 87664°— Bull. 223—15 1 



