18 BULLETIN 544, U. S. DEPARTMENT OF AGRICULTURE. 
The age at which, spruce begins to bear seed of good quality varies 
widely, depending on the soil quality, the exposure, and whether 
the tree is growing in the open or in the forest. In the virgin forest 
the production of seed is only indirectly a function of age and is 
more directly dependent upon size. The individual tree varies 
greatly as to the age when it becomes freed from suppression and 
enters upon a normal stage of development, thus gaining for itself a 
place in the full light of the upper crown classes. It appears from a 
study of the spruce made by the Bureau of Forestry 1 in cooperation 
with the Forest Commission of Maine in 1901, that in no case was a 
tree smaller than 5 inches in diameter at breastheight found bearing 
cones. The average age of spruce of this size in the virgin selection 
forest may be placed at about 100 years and in even-aged second- 
growth stands at from 20 to 30 years. Other observers have reported 
forest grown trees of three or four inches in diameter bearing seeds 
wherever their crowns were not directly under the shade of some 
other tree. The largest quantity and best quality of seed is pro- 
duced in the virgin forest by trees from 10 to 18 inches in diameter 
at breastheight. In other words, spruce in the forest begins to 
bear seed when the crown succeeds in reaching the light, and begins 
to bear heavily when the top of the crown thickens. At first a few 
cones are borne near the main stem below the last year's growth, and 
as the crown thickens and spreads the cones are borne on the side 
branches. The first seed produced is of very poor quality. 
In the open and under favorable soil and exposure conditions, 
seed production begins as early as the fifteenth or twentieth year, and 
heavy crops follow by the thirtieth or the thirty-fifth year. In the 
dense, even aged second-growth spruce stands the cones begin to be 
sparingly formed about the thirtieth year under the most favorable 
conditions; but a safe average for initial seed production in such 
stands would be not earlier than from the thirty-fifth to the fortieth 
year, with a full crop production about Hive or ten years later. Spruce 
continues to bear seed to an advanced age. 
Spruce seeds begin to mature between September 15 and October 1, 
depending upon climatic conditions. Seed collecting, therefore, can 
be most profitably confined between these dates; or if a larger amount 
of seed is required than can be collected during this period, the work 
should be begun earlier and timed so as to reach completion by Octo- 
ber. Upon full maturity the cones open and many of the seeds fall 
out, although not all, for frequently a considerable amount of seed 
can be seen on the surface of the late snows in February and March. 
After the cones are fully matured they are easily dislodged during 
lumbering; but if they are not disturbed, they remain on the trees 
until the next spring or early summer. The seed is fight and winged 
i Now the Forest Service. 
