INDUSTRIAL PLANTS 
Tig. 235.—Transverse section of white oak 
wood, 3. 
(Hartig.) 
planks, and is quite un- 
suited for most of the 
uses of ordinary wood. 
Like bamboo, the hard 
shell of the coconut, — 
and other materials 
sharing some of the es- 
sential properties of or- 
dinary wood but differ- 
ing from it decidedly in 
dq structure, the palm- 
trunk can scarcely be 
| regarded as a true wood 
at all. Such materials 
are best called pseudo- 
woods, to distinguish 
‘4 them from true woods 
Tic. 236.—Transverse section of elm wood, ?. 
Hartig.) 
Fic. 237.—Transverse section of ash wood, 3. 
(Hartig.) 
BIG. 
2338.—Transve 
wood, 3. 
rse section of walnut 
(Hartig.) 
which are always 
formed by a cambium 
layer. 
73. True woods. 
The following include 
the more important 
woods commonly used 
in this country :— 
Oak (Figs. 235, 242, 
243) is used extensively 
for heavy construction 
in common carpentry 
and shipbuilding, and 
in car and wagon work 
on account of its ex- 
traordinary strength; 
also in the manufacture 
of farm implements and 
parts of machinery be- 
cause of its hardness 
and toughness, while its 
unusual durability 
