Trees of the Northern United States 20 



■'>■!. With 2 visible scales in the triangular flattened bud; 

 pith sometimes \vith cavities; twigs pubescent, zig- 

 zag at the tip. Diospyros. (70). 



—54— 



o4. Outer bud scales more than 1. 5-j. 



•")4. Outer bud scale 1; twigs usually with brittle zones 

 and hence very easih' detached; stipular scars 

 present; bundle scars 3; pith small. Salix. (65). 



55. Pith diaphragmed but solid; bundle scars 3; no stip- 

 ular scars. Nyssa. (81). 



55. Pith not diaphragmed. 56. 



5G. Pith more or less 5-angled. 57. 



56. Pith cylindrical or nearly so. 61. 



57. P)uds clustered at the tip of the twig; bundle scars 



numerous, scattered. Quercus. (56). 



57. Buds not clustered at the tip. 58. 



58. Bundle scars numerous usually scattered. 59. 



58. Bundle scars 3. 60. 



59. Buds small with about 3 outer scales; twigs reddish 



or yellowish-brown, glabrous or pubescent; ter- 

 minal bud present or absent; stipular scars promi- 

 nent. Castanea. (55). 



59. Terminal bud large wath 4 or more visible scales, hairy 

 or peltate pubescent; lateral buds usually super- 

 posed; twigs tough. Hicoria. (61). 



fiO. Without stipular or self-pruning scars; crushed buds 

 fragrant, aromatic, not resinous, glabrous. 



Liquidambar. (46). 



(in. Stipular and self-pruning scars present; crushed buds 

 not fragrant though they may have a resinous odor, 

 resinous or if only slightly so then the twigs pubes- 

 cent or tomentose. Populus. (64). 



fil. Pith very large, light brown, bark not resinous, ill- 

 smelling; buds spherical or flattened at the apex, 

 often clustered at the tip of the twig, brown and 

 pubescent; bundle scars about 9 along the lower 

 edge of the very largo leaf scar; large trees. 



Ailanthus. (19). 



61. T'ith small, or if large an<I I)r..\\n thi-n tli<' b.irk 

 resinous. 62. 



