10 KEY, BASED UPON LEAVES. 



h. Ovate-oblong. 



Coarsely serrate with remote teeth, one at the end of each vein, 

 ciliate and covered with silky white hairs. 



16. FAGUS FERRUGINEA. 



Doubly and sharply serrate, nutlet inclosed in a papery sac. 



41. OSTRYA VlRGINICA. 



Unequally and sharply serrate, nutlet subtended by a leafy bract. 



42. CARPINUS CAROLINIANA. 

 h-. Ovate and 

 -I. Finely and closely serrate, smooth, whitish and reticulate-veined 



beneath i7. POPULUS BALSAMIFERA. 



f-. Doubly serrate and 



J. Thinnish ; petioles downy and of aromatic flavor. 



Bark of trunk yellowish-gray 17. BETULA LUTEA. 



Bark reddish-brown 44. BETULA LENTA. 



j 2 . Thickish and bark white 43. BETULA PAPYRACEA. 



</ 2 .* Veins incurved ; leaves 

 It. Orbicular-heart-shaped, thickish, 4-8 in. long. 



Acuminate 63. MORUS RUBRA. 



Obtuse or rounded at apex 97. POPULUS HETEROPHYLLA . 



/i 2 . Orbicular-ovate ; petioles laterally compressed ; leaves 



Coarsely dentate 18. POPULUS GRANDIDENTATA. 



Serrate-dentate 72. POPULUS TREMULOIDES. 



h\ Elliptical to obovate, conspicuously netted-veined. 



126. RHAMNUS PURSHIANA. 



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

 g. Narrow-lanceolate, very long-attenuate, tomentose on midrib above 



and petiole 45. SALIX NIGRA. 



</'-. Ovate-lanceolate to lanceolate, long-acuminate, 2-4 in. long; capsules 



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



With slender pedicels 71. SALIX AMYGDALOIDES. 



gr 3 . Oblong-lanceolate to lanceolate. 

 h . Minutely serrulate, 3-7 in. long ; petioles downy. 



140. SALIX LAEVIGATA. 

 7* 2 . Serrate with teeth sharply 



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



Mucronateand in 6-12 pairs 68. QUERCUS MUHLENBERGII. 



Finely glandular-serrate 55. PRUNUS PENNSYLVANIA. 



0r 4 . Oblanceolate to lanceolate-oblong, puberulous beneath. 



165. SALIX LASIOLEPIS. 



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



y*. Ovate ; petioles short, generally not more than \ in. 



163. ALNUS RHOMBIFOLIA. 



Long, very smooth and shining above 57. PYRUS COMMUNIS. 



</ 7 . Wedge-obovate, veins very prominent, 



Thin, smoothish and dull above 58. CRATAEGUS PUNCTATA. 



Thick, smooth and lustrous above 85. CRATAEGUS CRUS-GALLI. 



f/ 8 . Ovate-oblong, veins incurved and petioles 



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



h 2 . Without glands, 



Glabrous both sides, sharply serrate. 



59. AMELANCHIER CANADENSIS. 



Downy under-side and petiole 30. PYRUS MALUS. 



gr 8 . Lanceolate oblong, 1-3 in. long, about equally acuminate at both ends. 



111. FORESTIERA ACUMINATA. 



f 4 . Equilateral and truncate at base, 

 ff. Serrate-dentate with cartilaginous teeth 



Deltoid -ovate, rather long taper-pointed 48. POPULUS MONILIFERA. 



Deltoid-reniform, more abruptly pointed. . .194. POPULUS FREMONTII. 



Broadly deltoid 73. POPULUS DILATATA. 



f/-. Irregularly serrate or obscurely lobed 70. BETULA POPULIFOLIA. 



e 3 . Pinnately lobed ; lobes 



' f. Rounded at apex (not bristle-pointed) and 



