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



Graham County." Dr. Greene named and described this species in 

 1882. Later Dr. Rusby discovered an abundant growth of it in 

 canyons on the north slopes of the San Francisco Mountains, central 

 Arizona. 1 



DISTINGUISHING CHARACTERISTICS. 



Trees growing in the most favorable situations have narrow, sharply 

 conical crowns with large horizontal branches, straight, rather rapidly 

 tapering trunks, and long slender leaders, characteristics which dis- 

 tinguish the species at a distance from other associated trees. Such 

 trees are from 50 to 80 feet in height, with from 20 to 30 or more feet 

 of clear trunk. Young trees of this type are particularly straight, 

 with, very sharp, pointed crowns and horizontal branches. Trees in 

 exposed and otherwise unfavorable situations develop broad, rounded 

 or flat crowns, and seldom reach a height of more than 25 or 30 feet, 

 with very little clear stem. Diameter growth of Arizona cypress 

 varies from 14 inches to nearly 4 feet. (PI. Ill, right.) 



The trunk bark of large trees is from 1 J to 1J inches thick, and of 

 small ones from one-half to three-fourths of an inch. In color the 

 bark is a dull, ashy brown on the outside and pale to dark cinnamon- 

 brown when broken. It is firm, somewhat fibrous, and sharply and 

 deeply furrowed, the main narrow, flat, continuous ridges being con- 

 nected with small lateral ones. Bark on the branches, twigs, and 

 very young trunks is loosely scaly, the fresh smooth bark beneath the 

 scales being reddish to a dark yellowish-brown. The minute, scale- 

 like, sharp-pointed leaves (PI. I) have a whitish bloom, which gives 

 the foliage a pale silvery hue, especially pronounced in young trees. 

 The leaves are mainly without pits on the back; very rarely with 

 resinous glands, which when they do occur are exceedingly small. 

 This latter feature and the general absence of pits distinguish the 

 foliage of Arizona cypress from that of smooth cypress (Cupressus 

 glabra), which is commonly marked with large glandular pits. 

 Bruised twigs and foliage of Arizona cypress exhale a strong polecat- 

 like odor, while the trees themselves give off an odor which sometimes 

 can be detected at a distance of 100 yards. 



Mature cones of Arizona cypress (PL I, b), which ripen by Septem- 

 ber of the second season, vary in diameter from seven-eighths of an 

 inch to an inch, and remain on the trees for mam' years (PI. II, a, b), 

 changing with age and exposure from a dark umber-brown to ashy 

 gray. The conspicuous bosses, or protuberances, of the cone scales 

 are usually small and almost pricklelike on cones just matured 



1 Cupressus arizonica was introduced into England, France, and Germany about 32 years ago, where, 

 according to Elwes and Henry (Trees of Great Britain and Ireland, Vol. V, 1184, 1185, 1910), it grows thriftily 

 and has reached a height of from 15 to about 30 feet. 



