PINE TREES OF ROCKY MOUNTAIN" REGION". 21 



become better established than in the full sunlight. Pihon bears seed 

 very abundantly about every 2 years, but sometimes only at intervals 

 of 3 years. The wingless nutlike seeds always fall beneath or near 

 the trees. When fruiting trees occur on slopes, the seeds may be 

 washed some distance away and sometimes into depressions and 

 crevices where, when buried in soil or debris, they have the most 

 favorable opportunity for germination. Very few seeds that are left 

 on top of the ground germinate. As a rule, therefore, reproduction 

 is very sparse and much scattered, never dense. Scanty reproduction 

 is, however, doubtless due also to the fact that so large a part of each 

 seed crop is devoured by birds or mammals and gathered by settlers 

 and Indians. 



LONGEVITY. . 



Pifion is a very slow-growing tree, attaining an age of from 150 

 to 375 years or more. 



SINGLE-LEAF PINE. 



Pinus monophylla Torrey and Fremont. 



COMMON NAME AND EARLY HISTORY. 



This species is unique among all North American pines in having 

 single leaves. Generally it is known only as " nut pine " or " pihon." 

 It is desirable, therefore, in order popularly to distinguish this tree 

 from other nut pines, to adopt " single-leaf pine " as its common 

 name. 



Pinus monophylla was discovered in 1844 in Cajon Pass, San 

 Bernardino County, southwestern California, by Gen. John C. Fre- 

 mont, while on his expedition through Oregon and California. 1 The 

 first technical name applied to it, Pinus monophylla Torrey, was 

 published in 1845. Two years later (1847) the German botanist 

 Endlicher described and named it "Pinus fremontiana" and in 1860 

 Dr. Torrey designated it as Pinus edulis var. monophylla. The last 

 name applied to it is Pinus cembroides var. monophylla Voss. 2 



DISTINGUISHING CHARACTERISTICS. 



Single-leaf pine is characteristically a low, sprawling tree. Mature 

 trees have short trunks, which are rarely straight, and wide, rather 



1 Pinus monophylla was introduced into cultivation in Europe in 1848, where, according 

 to Elwes and Henry (The Trees of Great Britain and Ireland, V, 1057, 1910) some speci- 

 mens of it appear to have grown very slowly, although a few trees have grown more 

 rapidly and are healthy. The largest trees found by Elwes and Henry (1. c.) were from 

 13 to 20 feet high between 1908 and 1910. Single-leaf pine is occasionally cultivated in 

 eastern United States, where it is hardy as far north as eastern Massachusetts (Sargent, 

 Silva, XI, 53, 1897). Its growth there is, however, exceedingly slow. Like the pinon, 

 this pine is not attractive for ornamental planting. 



2 See footnote 4, page 16. 



