HOUGH'S AMERICAN WOODS. 



7i 2 . Ovate and 

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



beneath 47. POPULUS BALSAMIFERA. 



i 2 . Doubly serrate and 

 J. Thinnish ; petioles downy and 

 /c. Of aromatic flavor ; bark of trunk 



Yellowish-gray ; laminate 17. BETULA LUTEA. 



Reddish-brown 44. BETULA LENTA. 



A; 2 . Not of aromatic fla vor 236. BETULA OCCIDENTALS. 



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



gr 2 . Veins incurved ; leaves 

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



Acuminate 63. MORUS RUBRA. 



Obtuse or rounded at apex 97. POPULUS HETEROPHYLLA . 



ft 2 . Orbicular-ovate ; petioles laterally compressed ; leaves 



Coarsely dentate 18. POPULUS GRANDIDENTATA. 



Serrate-dentate 72. POPULUS TREMULOIDES. 



ft 3 . Broad ovate, acuminate serrate 218. POPULUS TRICHOCARPA. 



ft 4 . Elliptical to obovate, conspicuously netted-veined, above 



Glabrous 207. PRUNUS SUBCORDATA. 



Hairy along veins 126. RHAMNUS PURSHIANA. 



ft 5 . Ovate-lanceolate, pubescent beneath 209. PYRUS RIVULARIS. 



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

 g. Narrow-lanceolate, very long-attenuate; petioles 



Bearing dark glands 237. SALIX LASIANDRA. 



Not bearing glands, tomentose 011 midrib above and petiole. 



45. SALIX NIGRA. 

 gr 2 . Ovate-lanceolate to lanceolate, long-acuminate, 2-4 in. long; capsules 



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



With slender peduncles 71. SALIX AMYGDALOIDES. 



gr 3 . Oblong-lanceolate to lanceolate. 

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



140. SALIX LAEVIGATA. 

 ft 2 . Serrate with teeth sharply 



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



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



Finely glandular-serrate 55. PRUNUS PENNSYLVANIA. 



g 4 , Oblanceolate to lanceolate-oblong, puberulous beneath. 



165. SALIX LASIOLEPIS. 

 g 5 . Obovate-oblong, serrate, hairy beneath; length 



1-3 in., acute 208. PRUNUS MOLLIS. 



3-6 in. , long acuminate 5(5. PRUNUS AVIUM, 



gr 6 . Ovate ; petioles 



Short, generally not more than \ in 163. ALNUS RHOMBIFOLIA. 



Long; leaves very smooth and shining above. .57. PYRUS COMMUNIS. 

 gr 7 . Wedge-obovate, veins very prominent, 



Thin, snioothish and dull above 58. CRATAEGUS PUNCTATA. 



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



g*. Ovate-oblong, veins incurved and petioles 



h. With 2-4 glands, smooth 29. PRUNUS SEROTINA. 



ft 2 . Without glands, 



Glabrous both sides, sharply serrate. 



59. AMELANCHIER CANADENSIS. 



Downy under-side and petiole 30. PYRUS MALUS. 



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



111. FORESTIERA ACUMINATA. 



/*. Equilateral and truncate at base, 

 g. 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. 



g*. Irregularly serrate or obscurely lobed 70. BETULA POPULIFOLIA. 



c 8 . Pinnately lobed ; lobes at apex 

 /. Rounded (not bristle-pointed) and 



