554 IOWA ACADEMY OF SCIENCE 



ABIES BALSAMEA Mill. Balsam Fir. 



Leaves flat, edges tending down, y 2 inch to 1*4 inches long. 



Eesin ducts interparenchymal, lined by two layers of unlig- 

 nified cells. 



Vascular bundle surrounded by a slightly differentiated bundle 

 sheath of large, loose cells, lignified where joined together; 

 most of cells in pith below phloem lignified. 



Hypodermal cells not present or seldom so. No lignification of 

 epidermis except guard cells. 



Stomata in 4 to 8 rows each side of mid rib on lower surface. 



Material from Cass Lake, Minnesota. 



Plate LV. 



Figure 1. — Section of leaf of Abies balsamea. 



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

 A. balsamea. 



Figure 3. — Section through resin duct of leaf of A. balsamea. 



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

 balsamea. 



