14 BULLETIN" 13, U. S. DEPARTMENT OF AGRICULTURE. 
REPRODUCTION. 
Where it is planned to raise successive crops of trees, a comparative 
study of the methods of reproduction is important. The best and 
most economical means of reproduction are the natural ones afforded 
by the stand itself, provided these can be relied upon. Artificial 
methods are expensive, and require considerable' technical skill in 
carrying them out. On the other hand, since they do not require the 
presence of trees to seed the area, a free choice of seasons and sites is 
possible. With plantations the element of uncertainty which sur- 
rounds natural reproduction is avoided. 
The abundance and thrift of the second growth white pine on 
pastures and abandoned farms in the Northeast show that under 
proper conditions white pine can reproduce itself excellently by 
natural means. 
SEED PRODUCTION. 
The production of seed, like that of wood, depends upon the amount 
of food which the leaves manufacture. With other conditions equal, 
the more light a tree receives the earlier and more abundantly will it 
bear. Thus full-crowned, open-grown trees will begin to bear earlier 
and wall produce more seed than small-crowned forest trees of the same 
age and on the same kind of soil. Seed production is also earlier and 
more abundant on good soils than on poor. With plenty of light, 
white-pine saplings begin to bear cones when less than 20 years old. 
As a rule, however, seed are not produced hi abundance until the 
trees are from 35 to 70 years old, depending upon the amount of light 
received. As the trees increase in age they bear more prolific ally, 
and the proportion of fertile seeds increases. With the decline in 
vigor which attends old age there is probably a corresponding decline 
hi the amount and quality of seed produced, but white pine continues 
to bear fertile seed in abundance for at least 200, and probably 300, 
years. 
White pine cones require two years to mature. They begin to 
form hi June, and by the fall of the first year reach a length of 1 or 2 
inches. Thus it is possible to tell a year hi advance whether or not 
there will be a heavy seed crop. The cones reach then full length — 
5 to 1 1 inches — early hi the summer of the second year, and open in the 
fall, usually in September. A frost sufficiently severe to kill squash 
vines will often cause mature cones to open. Each cone bears from 
50 to 75 oval seeds — two on the upper face of each scale — about one- 
fourth of an inch long, and equipped with thin, membranous wings. 
A bushel of cones will yield from one-half pound to a pound of cleaned 
seeds, which run from 26,000 to 30,000 to the pound. 
Heavy crops of seed are borne at intervals of from 3 to 7 years, with 
occasional intervening years of lighter production. The same year 
