346 ESSENTIALS OF BOTANY 
For cabinet work the most valued of our hard. woods 
are black walnut, cherry, birch, and a good many spe- 
cies of oak and of ash. White walnut, red or sweet 
gum (Liquidambar), sycamore, and holly are also used. 
Fic. 234. Hickory (Hard-Wood) Forest near Southern End of 
Appalachian Highlands. 
(After Frye.) 
In structure the broad-leaved woods may be classed 
into two groups, — the ring-porous and the diffuse-porous 
kinds. 
In the former most of the conspicuous ducts (the cut-off 
ends of which appear as pores in the cross-section) are 
found in. the spring wood. In the latter the ducts are 
scattered somewhat generally throughout the wood of the. 
