KEY, BASED UPON LEAVES. 9 



e 1 . Sinuate-toothed, wliite-tomentose beneath 96. POPULUS ALBA. 



?. Cat-serrate or sublobate with slender petioles. 



Ovate, coarsely cut-serrate 83. PYRUS CORONARIA. 



Round-ovate, finely cut-serrate 86. CRAT.EGUS COCCINEA. 



e 9 . Crenate-serrate; petioles 1 in. or slightly less in length. 



82. PRUNUS CERASDS. 

 e 10 . Obscurely crenulate-toothed; leaves. 



Alternate, petioles long, mostly 1 in. or more. 



87. CORNUS ALTERIFOLIA. 



Opposite, petioles short (less than 1 in.) 88. CORNUS FLORIDA. 



e n . Doubly crenate serrate with glandular teeth 81. PRUNUS NIGRA. 



e 1 *. Doubly serrate, rhombic-ovate. 95. BETULA NIGRA. 



d 2 . Main ribs several pahnately- veined, etc. 

 e. Rib single at first but soon sending off a strong vein on each side and 



leaves 3-lobed, 2-lobed or entire 32. SASSAFRAS OFFICINALE. 



e 9 . Ribs three at first, but soon five by branching, leaves alternate, base of 

 petiole concave and fitting over the axillary bud. 



13. PLATANUS OCCIDENTALIS. 

 e 3 . Ribs 5-7 from commencement; leaves. 



/. Opposite base of petiole subtending (not Governing) the axillary end. 

 g. Moderately incised with broad lobes which are 



Sparingly sinnate-toothed 7. ACER SACCHARINUM. 



Irregularly serrate and notched . . .53. ACER RUBRUM. 



Sharply and finely doubly serrate. . . .79. ACER PENNSYLYANICUM. 



/*. Alternate, tendril bearing vine 78. Vms AESTTVAXIS. 



ff. Deeply incised with more or less acute sinuses and narrow divisions. 

 Star-shaped, lobes glandular serrate. 



60. LlQUIDAMBAR SLYRACIFLUA. 



Palmate, lobes incisely toothed 26. ACER DASYCARPTTM. 



C 3 . Needle-shaped without distinction of blade and petiole short, about 1 in. 



in length, soft and in fascicles of many each 23. LARIX AMERICANA. 



2 . Compound leaves. 



c. Palmate, with 7, obovate, serrate leaflets 6. AESCHLUS HLPPOCASTANUM. 



C' 2 . Pinnate and with au odd terminal leaflet, leaflets all 

 d. Petiolulate, leaflets. 



e. 21-41, each with one or two pairs of glandular teeth at its base. 



4. AlLANTHUS GLANDULOSUS. 



e 9 . 11-15, with prickle-like stipels, entire 80. ROBINIA PSEUDACACIC. 



With stipels, serrate 84. PYRUS SAMBUCIFOLIA. 



e 3 . 7-9, ovate or lance-oblong, entire or obscurely serrate. 



Petioles and branchlets glabrous 10. FRAXINUS AMERICANA. 



Petioles and branchlets velvety pubescent. .31. FRAXINUS PUBESCENS. 

 e 4 . Lateral leaflets. 



Petiolulate, irregularly toothed 54. ACER NEGUNDO. 



Sessile, subentire 77. PTELEA TRIFOLIATA. 



(P. Sessile or subsessile 



e. Numerous (15-17) and pubescent, especially along the petioles.and rachis. 

 f. Leaflets ovate -lanceolate, finely serrate; pubescence of short, rust- 

 colored clammy hairs. 



Fruit subovoid, viscid-pubescent 14. JUGLANS CINEREA. 



Fruit globose, roughly dotted (not viscid-pubescent). 



35. JUGLANS NIGRA. 

 f' 2 . Leaflets lance-oblong, coarsely serrate; pubescence of copious, longer 



and white hairs 5. RHUS TAPHINA. 



6 2 . Fewer (5-11). 



/. 5, quite glabrous; fruit a ridged nut about 1 in. long with thick epicarp. 



36. CARYA ALBA. 

 / 8 . 5-7 or 9, glabrous, epicarp thin; nut 



Small, thin-shelled 91. CARYA MICROCARPA. 



Larger, moderately thick shelled 85. CARYA PORCINA. 



2 



