WINTER KEY TO THE SPECIES OF 

 FRAXINUS 



a. Twigs prominently 4-angled; fruit falling in early autumn 



P. quad ran gulata, p. 219. 



aa. Twigs terete; fruit often persistent on the tree until mid- 

 winter or the following spring. 



b. Buds rusty-tomentose; twigs more or less downy 



P. pcnnsylvanica, p. 215. 



bb. Buds not tomentose; twigs not downy. 



c. Terminal bud black or nearly so, showing 3 pairs of 

 scales in cross-section ; bud-scales apiculate at the apex ; 

 samaras with broad wings, the seed portion flattish; 



bark flaky, rubbing off on the hand P. nigra, p. 221. 



cc. Terminal bud brownish, showing 4 pairs of scales in 

 cross-section ; bud-scales rounded at the apex ; samaras 

 with. narrow wings, the seed portion terete; bark ridged, 

 not flaky and rubbing off on the hand. 



d. Upper margin of leaf-scars deeply concave 



P. americana, p. 213. 



dd. Upper -margin of leaf-scars not concave, but straight 



across or projecting upward 



P, Pennsylvania* lanceolata, p. 217. 



211 



