14 BULLETIN 207, U. S. DEPARTMENT OF AGRICULTURE. 



side, a characteristic which clearly distinguishes this juniper from all 

 other native species. The leaves spread widely from the triangular 

 branchlets in groups of three at rather regular intervals, those of each 

 season's growth persisting for five or six years. Young plants of 

 other species, especially of Juniperus virginiana, have sharp-pointed 

 leaves similarly arranged, but much shorter and more slender. Male 

 and female flowers are usually borne on different twigs of the same 

 tree, though sometimes on different trees. The " berries" (PI. VII) 

 are mature at the end of the third summer, when they are very dark 

 blue, almost black, and coated with whitish bloom. The top of the 

 "berry" is conspicuously marked by three blunt projections, which 

 are points of the ovules (PI. VII). The soft flesh of the ripe fruit is 

 dry, resinous-aromatic, and sweet, and sometimes contains one, but, 

 commonly, from two to four hard, bony seeds. Birds and mammals 

 eat the berries greedily and thus assist in disseminating the seed ; other- 

 wise the fruit may remain on the branches during the following 

 winter or spring, occasionally even until late summer, before falling 

 to the ground. 



The heartwood of common juniper is pale, yellowish brown, heavy, 

 rather tough, very narrow-ringed, and exceedingly durable. Even 

 the largest tree form of this juniper known in the United States is too 

 small to be of any commercial value, though the more common 

 shrubby type forms a low, matted ground cover on the highest and 

 most exposed slopes and crests, effectively holding masses of snow 

 until stored water is gradually given up to the soil. 



OCCURRENCE AND HABITS. 



Common juniper occurs on dry knolls, sandy flats, rocky slopes and 

 ridges, interspersed among spruce and aspen, at elevations between 

 about 2,700 and 10,000 feet. 1 Generally, however, it grows at alti- 

 tudes between 4,500 and 8,000 feet. It is extremely tolerant of shade, 

 where, however, its growth is very much slower and its foliage less 

 dense than in full light. 



Common juniper is a fairly abundant seeder. Seed crops, some- 

 what larger than the ordinary, occur at irregular intervals of from two 

 to three years. On the whole, reproduction is rather sparse and 

 irregular, due no doubt to the fact that most of the berries are eaten 

 by birds, comparatively few of them reaching the ground in the imme- 

 diate vicinity of the mother plants, where conditions for germination 

 are most favorable. The fact that berries of this juniper require so 

 long a period to mature may also account in some measure for the lack 

 of natural production. 



1 The vertical range of the common juniper varies enormously throughout its world-wide distribution, 

 from sea level on the Pacific coast to 14,000 feet in the Himalayas. 



