SUMMER KEY TO THE SPECIES OF 
FRAXINUS 
a. Lateral leaflets sessile................00005 F. nigra, p. 221. 
aa. Lateral leaflets petioluled. 
b. Twigs, petioles and lower sides of leaves pubescent..... 
Ua OR TOA Eaton dena mame F. pennsylvanica, p. 215 
bb. ‘Twigs, petioles and lower sides of leaves essentially glab- 
rous. 
c. Twigs prominently 4-angled....F. quadrangulata, p. 219. 
cc. Twigs terete. 
d. Lower sides of leaves essentially of the same color 
as the upper; leaflet-margins rather finely sharp- 
SEPratey suas wcraauies F, pennsylvanica lanceolata, p. 217. 
dd. Lower sides of leaves paler than the upper; leaflet- 
margins entire or obscurely serrate..............0005 
oe ei Sees ia F. americana, p. 213. 
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