TORREYA 



LmHARf 



rtEW YOkK 



BOTANICrl. 



QAKUhN 



Vol. 21 No. 3 



May- June, 1921 



THE PHYLLOTAXY OF PHOENIX CANARIENSIS 



By Cornelius Beach Bradley 



Date palms of this species are frequently grown as ornamental 

 trees in and about Berkeley, California. They are mostly young 

 trees that are approaching maturity or have recently attained it. 

 As the leaves grow old and bend low toward the ground, they are 

 generally lopped oflf to get them out of the way, leaving the 

 stumps however in place on the trunk. Since these stumps per- 

 sist for years, they build up in time an authentic record of the de- 

 velopment and arrangement of the leaves, complete save where 

 accident or decay has marred it, and save also that it does not 

 include the earliest period of growth ; for through the enormous 

 expansion of the trunk during that stage, all the earliest leaves 

 are torn from their attachments and lost long before the regular 

 trimming of the leaves begins. This record of the leaf-stumps 

 was found to be of very great assistance in working out the phyl- 

 lotaxy of the tree, and is frequently cited as "the record" in 

 the discussion which follows. 



I 



I. A preliminary survey made it evident that the problem here 

 presented is not by any means the simple one usually encoun- 

 tered in a study of this kind, namely, the deciphering of a single 

 and a stable pattern, and the identification of it with one of the 

 "regular" patterns described in the textbooks. On the contrary, 

 all the ordinary clues were here completely lost in a maze of un- 

 ^ certainty caused by constant change of pattern. Only at a single 

 ^ point between infancy and maturity was there a pause where the 

 ~ wheeling ranks stood still long enough to be counted. Never 

 before had the writer encountered anvthing of this sort, nor from 

 2: 37 



