6 KEY, BASED UPON LEAVES. 



f 3 . Equilateral and acute at base, tapering both ways. 



gr. Linear-lanceolate, tomentose on midrib above and petiole. 



45. SALIX NIGRA. 

 gr 2 . Lanceolate or ovate-lanceolate, long-acuminate; capsules 



Sessile or nearly so .46. SALIX ALBA var. VITELLINA. 



With slender pedicels 71. SALIX AMYGDALOIDES. 



gr 3 . Oblong-lanceolate with teeth sharply 



Awn-pointed and in about 20 pairs 40. CASTANEA VESCA. 



Mucronate and in 6-12 pairs 68. QUERCUS MUHLENBERGII. 



Finely glandular-serrate 55. PRUNUS PENNSYLVANICUM. 



gr 4 , Obovate-oblong, serrate, hairy under surface. . .56. PRUNUS AVIUM. 



gr 5 . Ovate, very smooth and shining 57. PYRUS COMMUNIS. 



gr e . Wedge-obovate, veins very prominent. .58. CRATAEGUS PUNCTATA. 

 gr 7 . Ovate-oblong, veins incurved and petioles 



/*. With 2-4 glands, smooth 29. PRUNUS SEROTINA. 



7* 2 . Without glands, 



Glabrous both sides, sharply serrate. 



59. AMELANCHIER CANADENSIS. 

 Downy under-side and petiole 30. PYRUS MALUS. 



f 4 . Equilateral and truncate at base, 



gr. Serrate-dentate with cartilaginous teeth 



Deltoid-ovate 48. POPULUS MONILIFERA. 



Broadly deltoid 73. POPULUS DILATATA. 



gr 2 . Irregularly serrate or obscurely lobed. . . .70. BETULA POPULIFOLIA. 

 e*. Pinnatifid or lobed. 

 /". Moderately pinnatifid. 



gr. Oval, lobes bristle-pointed 15. QUERCUS RUBRA. 



Lobes obtuse and rounded 38. QUERCUS ALBA. 



gr 2 . Obovate or oblong, lyrate-pinnatifid and sinuses 



Nearly to the midrib and roundish ... 39. QUERCUS MACROCARPA. 

 Usually not over half-way to the midrib and acutish. 



66. Q. BICOLOR. 

 jf 2 . Deeply pinnatifid with mucronate teeth and broad rounded sinuses. 



69. Q. COCCINEA. 

 / 3 . Broad, truncate at both base and apex, and with two spreading lobes 



on each side 2. LIRIODENDRON TULIPIFERA. 



e 4 . Wavy and spinous-toothed, very thick 52. ILEX OPACA. 



e 5 . Undulately crenate-toothed; obovate to lanceolate.. 67. QUERCUS PRINUS. 

 C? 2 . Main ribs several palmately- 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 2 . Ribs three at first, but soon five by branching, leaves alternate, base of 

 petiole concave and fitting over the axillary bud. 



18. PLATANUS OCCIDENTALS. 



C 3 . Ribs 5-7 from commencement; leaves opposite, base of petiole subtend- 

 ing (not covering) the axillary bud. 

 /. Moderately incised with broad lobes which are 



Sparingly sinnate-toothed 7. ACER SACCHARINUM. 



Irregularly serrate and notched 53. ACER RUBRUM. 



f 2 . 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 DASYCARPUM. 



c 2 . 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. AESCULUS HIPPOCASTANUM. 



c 2 . Pinnate and with an odd terminal leaflet, leaflets all 

 d. Petiolulate. 



. Leaflets numerous, 21-41, each with one or two pairs of glandular teeth 



at its base ' 4. AILANTHUS GLANDULOSUS. 



e 2 . Leaflets 7-9, ovate or lance-oblong, entire or obscurely serrate. 



Petioles and branchlets glabrous 10. FRAXINUS AMERICANA. 



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



