22 
BUTjLETIX 933, U. S. DEPARTMENT OF AGRICULTURE. 
GROWTH OF INDIVIDUAL TREES. 
Walnut may be classed among the more rapid growing hardwoods. 
The fertility of the soil on which black walnut is usually found 
greatly facilitates the growth of the tree. The poorer the site, the 
slower are all phases of growth, in height, in diameter, and conse- 
quently in volume. Growth is also affected by the shade from adja- 
cent trees, and this accounts for the characteristic differences in form. 
The rate of diameter growth, on soils of equal quality, depends nor- 
mally upon the amount of foliage, and hence is slower in the small- 
crowned trees of the forest than in spreading-crdwned open-grown 
trees. When the trees are suppressed by the shade of taller trees, 
diameter growth is greatly decreased. 
HEIGHT GROWTH. 
Table 2 gives an idea of the average height growth of black walnut 
in comparatively open, pure stands in central Indiana and Ohio. It 
should be accepted as applicable only to " grove walnut " : 
Table 2. — Height growth of walnut in comparatively open 
stands in central Indiana and Ohio. 
Age. 
Height. 
Age. 
Height. 
Age. 
Height. 
Years. 
Feet. 
Years. 
Feet. 
Years. 
Feet. 
10 
13 
60 
72 
110 
84 
20 
35 
70 
75 
120 
85 
30 
53 
80 
78 
130 
86 
40 
62 
90 
81 
140 
87 
50 
68 
100 
82 ■ 
150 
88 
DIAMETER GROWTH. 
In the course of this study diameter-growth measurements were 
made on 128 trees located at 16 places in 6 States. While the number 
of trees thus scattered is too small to afford reliable data, the aver- 
age measurements shown in Table 3 will give a general idea of the 
average rate of diameter growth, breast high, of walnut under 
neither the best nor the poorest conditions : 
Table 3. — Breast-high diameter growth of walnut, based on 
measurements- of 128 trees widely scattered. 1 
Age. 
Diame- 
ter, 
breast 
high. 
Age. 
Diame- 
ter, 
breast 
high. 
Age. 
Diame- 
ter, 
breast 
high. 
Years. 
10 
20 
30 
40 
50 
Indus. 
1.2 
5.0 
8.8 
12.5 
15. 7 
Years. 
60 
70 
80 
90 
100 
Inches. 
18.3 
20.6 
22.2 
23.8 
25.0 
Years. 
110 
120 
130 
140 
150 
Inches. 
26.0 
26.9 
27.8 
28.5 
29.2 
•Distribution of measurements: Indiana, 37 trees from 5 localities; Ohio, 75 trees, 3 localities; Illinois, 
5trees, 1 locality; Virginia, 5 trees, 1 locality; New Jersey, 7 trees, 1 locality: Missouri. 3 trees, 1 locality. 
