552 IOWA ACADEMY OF SCIENCE 



KEY TO SPECIES OF ABIES. 

 1. Leaves flat. 



2. Resin duct lateral and interparenchymal. 



3. Hypodermal cells not present, stomata 4 to 8 rows 



on lower side A. balsamea 



3. Hypodermal cells present. 



4. Stomata on lower surface only, 8 to 12 rows 



A. Fraseri 



4. Stomata on upper and lower surfaces, 8 to 10 



rows below, indefinite number above 



A. lasiocarpd 



2. Resin ducts lateral, touching lower epidermis. 



3. Hypodermal cells present on dorsal side in con- 

 tinuous layer, or around entire periphery, 

 except along bands of stomata. 

 4. Stomata not present on dorsal surface. 



5. Leaf small, deeply grooved. Margins 

 curving up. Stomata in bands of 6 



to 8 rows each A. amabilis 



5. Leaf very long, flat or slightly rounded 

 on upper side. Eight to sixteen rows 



of stomata in each band A. venusta 



4. Stomata present on both dorsal and ventral 



surface, leaf deeply notched above.. A. nobilis 

 3. Hypodermal cells present only in lateral angles of 

 leaf, and along ventral midrib or in 

 groups of 2 or 3 along dorsal side. 



4. Stomata on ventral surface only A. grandis 



4. Stomata on both dorsal and ventral surfaces 



A. concolor 



1. Leaves 4-angled or rounded. 



2. Bundle sheath obscure. Vascular bundles close together. 

 The same number of rows of stomata on all sur- 

 faces A. magnified 



2. Bundle sheath distinct. Vascular bundles far apart. 

 Rows of stomata more numerous on lower surface. . . 

 A. nobilis 



ABIES FEASERI Poir. Balsam Fir. 



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



Resin ducts large, lateral and more or less touching ventral epi- 

 dermis, lined with two rows of cells. 



Vascular bundles small, enclosed in a sheath of large, round, 

 loosely joined cells; xylem bundles small and close together, 

 separated by a band, of thin walled cells, one row wide. The 

 thin walled irregular cells present below and between phloem 

 are lignified. 



Hypodermal cells present in angles made by ducts and epider- 

 mis, and in small number along midrib. 



Epidermis not lignified. 



Stomata present on lower surface in band of 8 to 12 rows each 

 side of midrib. 



Material from Jamaica Plains, Massachusetts. 



Plate LIV. 

 Figure 1. — Section of leaf of Abies fraseri. 

 Figure 2. — Section of epidermis and stomata, leaf of A. fraseri. 

 Figure 3. — Section through resin duct of leaf of A. fras< ri. 

 Figure 4. — Section of vascular cylinder, leaf of A. fraseri. 



