SEED PRODUCTION OF WESTERN WHITE PINE. 13 



length and width of the crown, which has been accepted as a most 

 decisive influence in seed production, there are other factors that 

 affect the amount of viable seed produced by a tree, such as the size 

 of the cones, average number of seed in a cone, size of the seed, its 

 germinability, the age of the tree, and the still little understood 

 individual energy of each tree in producing seed. 



2. The largest amount of germinable seed was invariably produced 

 by trees chiefly of the first and also of the second crown class. The 

 largest amount of germinable seed recorded (2 J ounces) belonged 

 to two trees of crown Class I, and in only one case has this amount 

 been closely reached by a tree of crown Class II. Crown development 

 thus seems to be the most important factor in the seed production 

 of trees. 



3. The age of the trees evidently has an effect upon the amount 

 and quality of seed produced. Thus the younger trees (in plot No. 

 4), ranging from 72 to a little over 100 years in age, have produced 

 practically in all three crown classes a larger quantity of germinable 

 seed than the older trees. Apparently the age has also something to 

 do with the average length of the cones, since the younger trees 

 possessed, on an average, longer cones which yielded a larger number 

 of pure seeds per cone than the older trees. The germination per- 

 centage was also greater in the younger trees than in the old ones; 

 the highest germination percentage reached (90) was found in a tree 

 72 years old, while the highest found in the older trees was 67.5. 



4. The relation between the length of the cone and the size of the 

 seed (the number of seed per pound) is clearly shown. Thus the 

 longest cones, 8 inches and over, yielded about 22,000 seed to the 

 pound, while cones 5 inches long occasionally yielded as many as 

 57,000 seed to the pound. 



5. The vigor of growth apparently influences favorably the amount 

 and quality of seed produced. Thus trees which grew at the rate of 

 0.19 of an inch in diameter and about 1.25 feet in height annually 

 produced a larger amount of germinable seed than trees which grew 

 at a slower rate. This, however, may be indirectly the effect of the 

 age of the tree, since the younger trees have not yet passed the period 

 of most rapid growth. 



6. While a relation between the size of the seed and its germina- 

 tive vigor * is not clearly brought out, yet there seems to be a tendency 

 for the larger seeds to have the highest germinative vigor. This ten- 

 dency is shown in Table 6. 



1 The germinative vigor is gauged by the percentage of seed which germinated within 144 days after 

 being sown. 



