THE LEAF 



SI 



the distichous arrangement, one cycle includes two 



leaves arranged in two orthostichies 



and one complete turn of the spiral line 



round the stem: the numerator of the 



fraction J, used to designate this phyllo- 



taxy, indicates the number of complete 



turns of the spiral round the stem to 



form one cycle, and the denominator the 



number of leaves or, what is the same, 



the number of orthostichies in the cycle. 



In the tristichous phyllotaxy, denoted 



by fraction J, one cycle includes three 



leaves arranged in three orthostichies 



and one complete turn of the spiral ; in 



the pentastichous phyllotaxy, denoted by the fraction 



f, the cycle includes five leaves arranged in five 



orthostichies and two complete turns of the spiral. 



Fig. SI.— Part of 

 Stem of Date Palm 

 — Khejur (Pha- 

 liix syh'esiris) — an 

 example of Para- 

 stichy 



i 2 3 



* T ^ 



figr- 52.— Piagram shewing Phyllotaxis of Leayes (long;itmlioa,l) 



