533 IOWA ACADEMY OF SCIENCE 



PICEA ENGELMANNI. Engelm. Engelman Spruce, 

 White Spruce. 



Leaves 4-angled, 1 inch to 1% inches long. 



Resin ducts 2 (in some leaves 1 or both are missing), very large 

 (as large as vascular cylinder), touching epidermis on ventral 

 side, lined with 2 layers of lignified cells. 



Vascular bundles — Xylem most noticeably undivided, pith cells 

 above xylem lignified, large irregular cells in pith below 

 phloem lignified, cells of bundle sheath lignified where joined. 



Hypodermal cells present around entire periphery in 1 layer 

 with increases to 2 to 3 layers at angles, heavy walled and 

 lignified. 



Parenchyma walls slightly corrugated. 



Stomata in 3 to 5 rows on each side. 



Material from Herbarium of Iowa State College. 



Plate XLIV. 



Figure 1. — Section of leaf of Picea Engelmanni. 



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

 P. Engelmanni. 



Figure 3. — Section through resin duct of leaf of P. Engel- 

 manni. 



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

 Engelmanni. 



