434 ACERACEAE 



Pa. Northampton, Bucks, Lehigh, Delaware and Chester Co. 



Tertiary, o: Cretaceous, scattered, mostly near glacial terraces 

 along the Delaware: Older Formations, increasing northward. 

 117-220 days. Sea level-3,ogo ft. 



ACERACEAE 

 I. Acer [Tourn.] L. 



Leaves simple, palmately lobed. 



Flowers in dense sessile lateral clusters, unfolding before the 

 leaves. 

 Petals none; ovary tomentose; samaras divergent. 1. .4. saccharinum. 



Petals present; ovary glabrous; samaras incurved. 

 Leaves not conspicuously paler beneath than above, 



northern. 2. A. rubrum. 



Leaves conspicuously paler beneath than above. 3. A. carolinianum. 



Flowers corymbose, unfolding with the leaves. 



Leaves pale and nearly glabrous beneath. 4. A. Saccharum. 



Leaves green and pubescent, at least on the veins, 



beneath. 5. A. nigrum. 



Flowers racemose, terminal, unfolding after the leaves. 



Racemes drooping; leaves finely serrate. 6. .4. pennsylvanicum. 



Racemes erect; leaves coarsely serrate. 7. .4. spicatum. 



I. raves pinnate. 8. A. Negundo. 



1. A. saccharinum L. Along streams: N. B. to Fla., S. Out., 



Dak., Neb. and Ind. Terr. 



Conn. Unknown along the Sound as a wild plant, increasing 

 northward especially up river valleys. 



N. Y. Very rare, if at all as a wild tree on L. I. and S. I. ; rare in 

 the Bronx; unknown up the Hudson Valley to the Highlands, 

 thence increasing but not common northward; common every- 

 where as an escape. 



N. J. Known only in the drainage of the Delaware in Sussex, 

 Warren, Hunterdon and Camden counties, and in the drainage 

 of the Pasaic and upper Raritan rivers so far as wild trees are con- 

 cerned. Perhaps all others are derivatives of cultivated speci- 

 mens; found as an escape in most parts of the state, except the 

 pine-barrens. 



Pa. Monroe, Northampton, Bucks, Delawareand Chester counties. 

 A rare and highly localized plant in our area. Except for its 



greater profusion in river-valleys, apparently without significant 



distributional features. 



2. A. rubrum L. In swamps and low grounds: N. B. to Man. and 



southward. 



