PINE TREES OF ROCKY MOUNTAIN REGION. DAL 
become better established than in the full sunlight. Pinon bears seed 
very abundantly about every 2 vears, 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 débris, 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 875 years or more. 
SINGLE-LEAF PINE. 
Pinus monophylla Torrey and Frémont. 
COMMON NAME AND EARLY HISTORY. 
This species 1s unique among all North American pines in having 
single leaves. Generally it is known only as “nut pine” or “ pifon.” 
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. Fré- 
mont, while on his expedition through Oregon and California.t_ 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.” 
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 monophyila 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 oy 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 pifon, 
_ this pine is not attractive for ornamental planting. 
2See footnote 4, page 16. 
