1917] BRUSH—SYCAMORE WOODS 481 
the elements which serve as distinguishing characters must be mag- 
nified, to some extent at least, for positive identification. The 
chief distinguishing characters of the sycamore woods are the color 
of the sapwood and heartwood and the size of the pith rays. The 
average weight? and hardness of these woods differ very little, and 
hence they cannot be depended upon as distinguishing characters. 
Specific gravity and the weight per cu. ft. are shown in table I. 
TABLE I 
Species Specific gravity ve taie tock 
Platanus occidentalis ce oO. 5678 35-39 
Platanus Wrightii.......... 0.4736 29.51 
Platanus racemosa.......... 0.488 30.41 
SAPWOOD AND HEARTWOOD 
While the sapwood and heartwood usually do not show distinct 
limits, they are easily distinguishable from one another by their 
color. The sapwood of the eastern sycamore is light brown, and 
the heartwood has a decidedly reddish tinge; the sapwood of Cali- 
fornia and Arizona sycamores is a yellowish white, while the heart- 
wood is somewhat darker and only slightly tinged with red. In 
all species the sapwood occupies only a thin zone. Both the color 
and thickness of the sapwood and heartwood, however, are very 
variable, depending probably to some extent upon the age, climate, 
soil conditions, and the general health of the tree. Trees growing 
in low or moderately wet soil usually develop thicker sapwood than 
those found on higher well drained ground. As a rule the eastern 
species has a thicker sapwood than the western ones. 
ANNUAL RINGS OF GROWTH 
Annual rings of growth in all three species (pls. XXXII-— 
XXXIV, ew and Jw) are clearly visible to the unaided eye. Each 
ring is defined from the next layer by a more or less distinct 
a Ble ESO ry 
? The Hardwood Manufacturers’ Association h 
sycamore lumber to be 3200 pounds per 1000 board feet. The testi per board foot 
of the western species has not been listed. 
