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BULLETIN 223/ U. S. DEPARTMENT OF AGRICULTURE. 



antrorse pinnae. They may lie nearly in the plane of the blade 7 but 

 they usually form angles back of that plane which must be measured 

 dorsally. 



Toward the base of the blade the groups may irregularly coincide 

 on opposite sides of the rachis, giving the pinnae a tufted appearance 



Fig. 6. — Micrometer, reading to 0.001 of an inch, 

 for determining the comparative thickness of 



pinnaa of date leaves of different varieties. FlG - 7.— Combination 2-foot rule and protractor with 



vernier for determining the angles at which date- 

 i 1 • ii p leaf pinnae diverge from the rachis. 



and leaving naked spaces 01 sev- 

 eral inches between them. In other examples the groups may be 

 coalescent through the caudate pulvini, or they may be so crowded 

 that the pinnae overlap like the slats in a window blind. 



Figure 5, E, shows on the left side of a section a triple group in the 

 middle, but coalescent with the groups above and below by the 

 caudate pulvini of the antrorse pinnae. 



