KEY, BASED UPON LEAVES. 9 



i 2 . 1-2 in. long and only slightly inequilateral. 



114. PLANERA AQUATICA. 



Flowers and fruit in fascicles 33. ULMUS AMERICANA. 



Flowers and fruit in racemes 34. ULMUS RACEMOSA. 



f' 2 . Equilateral and obtuse, rounded or cordated at base. 

 g. Veins straight or nearly so, leaves thinnish, 

 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 2 . Ovate and 

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



beneath 47. POPULUS BALSAMIFERA. 



< 2 . 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*. Thickish and bark white 43. BETULA PAPYRACEA. 



gr 2 . Veins incurved. 

 fl. Orbicular-heart-shaped, leaves thickish, 4-8 in. long. 



Acuminate ... 63. MORUS RUBRA. 



Obtuse or rounded at apex 97. POPULUS HETEROPHYLLA. 



h?. Orbicular-ovate; petioles laterally compressed, 



Coarsely dentate 18. POPULUS GRANDIDENTATA. 



Serrate-dentate 72. POPULUS TREMULOIDES. 



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



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



and petiole 45. SALIX NIGRA. 



(7 2 . 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. 

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



140. SALIX LAEVIGATA. 

 h?. Serrate 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 PENNSYLVANIA. 



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



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



gr 6 . Wedge-obovate, veins very prominent, 



Thin, smoothish and dull above 58. CRATAEGUS PUNCTATA. 



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

 gr 1 . Ovate-oblong, veins incurved and petioles 

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



2 



