TREES. 15 
. Pith chambered: fruit fleshy: calyx large. Diospyros. 
Pith continuous. 59. 
. Buds naked. Rhamnus. 
Buds scaly. 60. 
6c. Bud-scales several, 2-ranked. 61. 
Bud-scales in more than 2 ranks. 62. 
61. Fruits thin and winged. Ulmus. 
Fruit not winged, tuberculate: leaves small. Planera. 
62. End-bud present. 63. 
End-bud often absent: pith 5-sided: twigs stout. Castanea. 
End-bud always absent: twigs slender. 64 
63. Buds elongated: pith 5-sided: fruit berry-like. Amelanchier. 
Buds short: pith 3-sided: fruit dry. Betula. 
64. Bud-scales striate. 65. 
Bud-scales not striate. 66. 
65. Bark rough: fruit hop-like. Ostrya. 
Bark cherry-like or white or papery. Betula. 
66. Fruit ribbed, with hastate bract. Carpinus. 
Fruit not ribbed: leaves rough. ; Zelkova. 
67. Pith rather large, or star-shaped. 68. 
Pith not star-shaped, or if so, buds stalked. 7o. 
68. Buds with lower scales at the side. 69. . 
Buds often gummy, with lowest scale in front. Populus. 
69. Leaves entire or pinnately lobed. Quercus. 
Leaves palmately lobed. Liquidambar. 
70. Buds stalked, or developing the first season. 7I. 
Buds not stalked. 72. 
71, Leaves palmately lobed. Liquidambar. 
Leaves pinnately toothed or lobed. Alnus. 
72, Leaves with nectar-glands at base or on petiole. 73. 
Leaves without nectar-glands. 75. 
-3. Twigs green or red: leaves drooping. Prunus (Amygdalus). 
Twigs duller. 74. 
74, Leaves rounded: fruit nearly sessile. Prunus (Armeniaca) 
Leaves rather lanceolate: flowers stalked. Prunus. 
70%, Pith chambered. 76. 
Pith continuous. 73 
