542 IOWA ACADEMY OF SCIENCE 



TSUGA CABOLINIANA Engelm. Hemlock. 



Leaf flat, straight, 1/3 to % inch long. 



Resin duet 1, small, central, touching hypodermal cells adjoin- 

 ing epidermis; lined with a layer of flat lignified cells. 



Vascular bundle enclosed in a sheath of large, round, loosely 

 joined cells. Xylem bundle small and separated by a layer 

 of large thin walled cells. Two groups of lignified cells at 

 each side of phloem. 



Hypodermal cells in angles formed by epidermis and resin duct 

 at edges of leaf and a few scattered singly on dorsal side. 



Stomata in bands of 7 to 8 rows each on ventral side either 

 side of midrib. 



Material from Biltmore, North Carolina. 



Plate XLIX. 



Figure 1. — Section of leaf of Tsuga caroliniana. 



Figure 2. — Section through epidermis and stoma of T. caro- 

 liniana. 



Figure 4. — Section through vascular cylinder and resin duct 



of leaf of T. caroliniana. 



