TREES xvii 



62. Twigs and leaves hairy. p. 30. Broussonetia. 

 At most rough or velvety or downy. p. 31. Morus. 



63. Twigs moderate, or if slender pith continuous. 64. 

 Twigs slender: pith commonly chambered. p. 34. Celtis 



64. Leaves entire, glabrate. p. 70. Cercis. 

 Leaves serrate. 65. 



65. Twigs slender: peduncle becoming fleshy, p. 98. Hovenia. 

 Twigs stouter: peduncle slender, bracted. p. 101. Tilia. 



66. Pith more or less spongy or chambered. 67. 

 Pith continuous. 68. 



67. Fruit fleshy: calyx large. p. 125. Diospyros. 

 Fruit dry, winged. p. 126. Halesia. 



68. Buds naked. p. 97. Rhamnus. 

 Buds scaly. 69. 



69. Bud-scales 2-ranked. 70. 

 Bud-scales in more than 2 ranks. 71. 



70. Fruit thin and winged. p. 32. Ulmus. 

 Fruit not winged, tuberculate: leaves small, p. 33. Planera. 



71. End-bud present on spurs. 72. 



End-buds always absent: twigs slender. 74. 



72. Pith very small, 3-sided. p. 25. Betula. 

 Pith 5-sided. 73. 



73. Twigs slender: leaves finely toothed, p. 60. Amelanchier. 

 Twigs stouter: leaves coarsely toothed. p. 28. Castanea. 



74. Bud-scales striate. 75. 

 Bud-scales scarcely striate. 76. 



75. Bark rough: fruit hop-like. p. 24. Ostrya. 

 Bark white or papery, or aromatic. p. 25. Betula. 



76. Fruit ribbed, with hastate bract. p. 25. Carpinus. 

 Fruit not ribbed: leaves rough. p. 34. Zelkova. 



77. Pith rather large, or star-shaped. 78. 



Pith not star-shaped, or, if so, buds stalked. 82. 



