CYPRESS AND JUNIPER TREES OF ROCKY MOUNTAIN REGION. 31 



of an inch thick on trunks 6 to 8 inches through to about 3^ inches on 

 the larger ones, has its flat ridges sharply cut into rectangular plates 

 (PL XX). Externally it is usually weathered to a bright ashy-gray, 

 beneath which the color is a dull, dark chocolate-brown. When the 

 slender twigs shed their leaves, they have smooth, reddish purple- 

 brown bark, which becomes scaly as the branchlets grow larger. 



The foliage is a pale blue-green; the alternately opposite pairs of 

 minute, scalelike leaves (PI. XIX), closely pressed and overlapping 

 each other, are arranged in four ranks, giving the twigs a four-sided 

 appearance. Each leaf bears a tiny but conspicuous resin-gland on 

 its back. Leaves of young shoots and seedlings (PL XIX, h, c) are 

 narrowly lance-shaped and keenly pointed. The margins of the 

 leaves are minutely toothed. 



Male and female flowers are borne on different trees. The berries, 

 which are matured by October of the second year, vary in shape 

 from spherical to slightly elongated, and may be from about three- 

 eighths to nearly one-half of an inch in diameter or length. Their 

 surface is more or less marked by the points of united female flower- 

 scales, and further roughened by irregular little knobs (PL XIX). 

 The firm, deep purplish-brown skin of the berries is covered with a 

 whitish bloom. The flesh of mature berries is dryish and resinous, 

 that of immature ones being very resinous. They contain from 1 to 

 4 brownish, pointed, distinctly grooved seeds (PL XIX, a), the bases 

 of which bear a short, two-lobed scar (hilum). The seed-leaves are 

 two in number, pointed, and about one-half an inch long. Ripe 

 berries are shed rather slowly, in some cases continuing to fall during 

 the winter and summer following their maturity. 



The wood of alligator juniper is rather light, soft, brittle, and very 

 narrow-ringed. The sapwood is comparatively thin and of a pale 

 straw-color ; the heartwood is light brown with a faint reddish tinge, 

 irregularly marked with paler streaks. Seasoned heartwood is dur- 

 able. Alligator juniper is locally much used for fuel and fence posts, 

 a number of which are often split from large clear logs (PL XX). 

 The wood "cuts" freely, with an easily parted chip, a quality which 

 would make it useful for lead pencils, and the probable future use of 

 the best grades for this purpose is likely to give the wood considerable 

 commercial value. 



OCCURRENCE AND HABITS. 



Alligator juniper is of frequent occurrence throughout its range, 

 sometimes in very scattered, open, pure stands, but oftener mixed 

 with Emory oak, Arizona oak, blue oak, piflon, and Mexican piflon. 

 It grows in the driest rocky and gravelly soils on mountain slopes, 

 plateaus, and canyon sides, where it is likely to be much stunted and 

 distorted. The best developed trees are found in moist, deep washed 



