530 IOWA ACADEMY OF SCIENCE 



PICEA CANADENSIS B. S. & P. White Spruce. 



Leaves 4-angled, 1/3 to % inch long. 



Resin ducts none or rarely one. 



Vascular bundles — Xylem bands separated by one row of thin 

 walled cells, cells of pith lignified below phloem, also a few 

 thick walled lignified cells below phloem, bundle sheath not lig- 

 nified. 



Hypodermal cells in one layer around entire periphery ligni- 

 fied. 



Parenchyma walls smooth. 



Stomata in 3 to 4 rows on each side of leaf. 



Material from Campus of Iowa State College. 



Plate XLIII. 



Figure 1. — Section of leaf of Picea canadensis. 



Figure 2. — Section through epidermis and stomata of leaf of 

 P. canadensis. 



Figure 4. — Section through vascular cylinder of leaf of P. 

 canadensis. 



