Table 1 gives a comparison of the different classes of trees with 

 reference to germination and yield. 



The cones were air dried. Each sample was placed in a 2-bushel 

 sack immediately after collecting and kept there through the entire 

 process of drying. The amount placed in each sack was in no case 

 more than 1 bushel, though by the time the cones were fuUy opened 

 the volume had about doubled. The drying process, which involved 

 daily turning of the sacks, required about six weeks. No rain or snow 

 fell in the meantime. The seeds were extracted by first shaking the 

 cones violently in an iron tub and then striking each cone separately 

 against the side of the tub. They were cleaned by rubbing between 

 the hands, and later allowing the wings to blow out by pouring the 

 mass slowly from one vessel to another in a light breeze, care being 

 exercised to prevent the light, hollow seed shells from blowing out, 

 because obviously these should be considered in the germination tests. 



The germination tests l were made at Washington by planting 200 

 seeds from each sample in a sand flat and subjecting them to a hot- 

 house temperature of 60 F. The duration of the test was 52 days, 

 during which period counts were made every two or three days. 



The terms "blackjack" and "yellow pine" will be used in this 

 circular to distinguish two forms of the species Pinus ponderosa. 

 "Blackjack" is the local name applied to young, vigorous trees 

 characterized by a dark, almost black bark. "Yellow pine" is the 

 local name applied to the older trees characterized by a yellowish or 

 reddish brown bark. Lumbermen generally regard the two forms 

 as distinct species, but the only difference is that due to age. 



From Table 1 the following deductions may be made : 



GERMINATION. 



Seed from young trees shows a higher germination than seed from old, 

 mature, or overmature trees. The 38 blackjacks used in this test 

 give a germination of 76 per cent, against 68 per cent for the 60 yellow 

 pines. A comparison of 20 trees near Cliffs on this Forest in 1908 

 gave a germination of 68 per cent for yellow pine, against 80 per cent 

 for blackjack. Classifying both blackjack and yellow pine accord- 

 ing to age, by decades, the germination per cent is found to fall 

 with the increase in years. This decline is, however, by no means 

 regular. For instance, 5 trees 220 years old show an average germi- 

 nation of only 50 per cent, while 2 trees 390 years old show an aver- 

 age of 75 per cent. Dividing all trees, both yellow pine and blackjack, 

 into three age classes, namely, below 140 years (8 to 14 inches diam- 

 eter breast-high), 140 to 250 years, and 260 to 400 years, the average 

 germination per cents are found to be 81, 71, and 63, respectively. 



i Conducted by Mr. N. IT. Grubb. Office of Silvics. 

 [Cir. 196] 



