44 BOTANICAL SURVEY OF THE CCEUR DALENE MOUNTAINS. 



greatest density lies between 050 and 850 meters (2,100 and 2,800 feet) 

 elevation. Although of wide distribution, it is far from equally abun- 

 dant in all localities. In tbe St. Mary valley it is especially plentiful 

 in the basaltic region, both along the main stream and its tributaries. 

 Above these areas it thins out rapidly, and ceases almost entirely at a 

 distance of about 52 kilometers (.32 miles) from the confluence of this 

 river with the St. Joseph. The line of demarkation is quite sharply 

 drawn, and is clearly due to a greater humidity than is compatible with 

 the proper growth of the tree. In the St. Joseph valley the species 

 extends a distance of above SO kilometers (50 miles) from its outlet into 

 Lake Cteur d'Alene. Around this lake and on the low, broken country 

 which extends from this point to the northeast and southeast until it 

 joins the valley of the Cceur dAlene the tree is more plentiful than 

 elsewhere. It follows up the valley of the South Fork to the foot of 

 the main divide of the Bitter Boots, but in the upper or canyon part of 

 the valley it is almost wholly confined to the mountain slopes which 

 have a southern exposure. 



In the North Fork basin the tree occurs on all the more rocky and 

 open hillsides in the eastern part which face the south. In the large 

 interior and western portions of this area the species is nearly absent. 

 Now and then a few individuals of mature age are seen on some bare, 

 rocky point of a projecting spur, but their numbers are very small and 

 I have never known any of them to produce cones. 



The yellow pine in the Occur d'Alenes varies in height from 30 to 05 

 meters (98 to 213 feet), ranging in diameter up to 1.5 meters (4.9 feet). 

 The largest diameter which has come under my observation was 2.3 

 meters (7.5 feet); a fair average is 1 meter (3.3 feet). The species may 

 be considered as mature at 150 years of age. At a certain period in 

 its existence the tree ceases to grow in height. This is marked by the 

 loss of the leader, which begins to fork and branch out in a horizontal 

 manner. Thenceforth it only increases its diameter, and the process 

 is a slow one. In trees 200 years old and upward the annual rings 

 for a distance of 7 cm. (2.5 inches) or more from the periphery will 

 often not average more than 1 nun. (±- inch) apart. The age at which 

 the species ceases to grow in height varies with the individuals and 

 the conditions under which they are placed as regards soil, humidity, 

 and elevation. I should consider 150 years an average age. The sap- 

 wood of the tree is white, almost free from resin, and constitutes from 

 one-third in young trees to one-sixth or one eighth in old of the total 

 diameter. It is not durable if subjected to alternate wet and dry con- 

 ditions. In sawing, the larger part of this is slabbed. "The heartwood 

 is of a yellowish color, and is always more or less resinous, sometimes 

 exceedingly so. It is very durable, but objectionable and not lit to 

 use for many purposes on account of the quantity of resin with which 

 it is charged. The tree would doubtless furnish a superior article of 

 tar, especially the roots, many of which in dry soils are so highly 



