10 WESTERN YELLOW PINE IN ARIZONA AND NEW MEXICO. 
them usually begin to decline in vigor when from 180 to 220 years 
old. From all stem analyses taken at random in timber sales on the 
Forests of the Southwest, the age of the oldest yellow pine was 418 
years, while that of the oldest veteran yet recorded for the region was 
489 years. It is likely that the periodic droughts of the Southwest 
tend to shorten the tree’s life. 
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ROOT SYSTEM. 
Western yellow pine has a deep-reaching tap root and exceedingly 
long and strong laterals. Development of the root system in the 
seedling stage is very rapid. Seedlings sown on April 20, 1910, at 
the Gallinas nursery had an average height on October 3, after the 
growing season was over, of 1.12 inches and a tap root of 14.5 inches. 
Two-year transplants at the same nursery were 3.1 inches in height 
and had a tap root of 32.3 inches. Seedlings in the forest have 

