A tree to 75 ft in the wild state (sometimes taller in favoured localities); bark on young trees red, smooth, peeling in thin flakes, on mature trees dark brown, furrowed and fibrous. Leaves closely overlapping and scale-like, pale green to grey-green, more rarely blue-green, acutely pointed, about 1⁄16 in. long; resin-pits usually inconspicuous and inactive. Branchlets irregularly arranged, the final subdivisions four-sided, 1⁄20 in. in diameter. Cones short-stalked, globose, 3⁄4 to 1 in. in diameter, glaucous; scales six (rarely eight), slightly rising towards the middle, where there is a pyramidal, pointed boss.
Native of the S.W. United States and N. Mexico (where it may intergrade with the closely allied C. lusitanica); discovered by Greene in 1880 in S.E. Arizona and also found in S.W. New Mexico. Most of the trees cultivated in Europe as C. arizonica or “var. bonita” belong to the following species, which is a close ally and not recognised by all authorities:
C. glabra Sudw. C. arizonica var. bonita Hort. and of many authors, not Lemm. – This species occupies parts of Arizona well to the west of C. arizonica, from Coconino Co. to the Mazatzal Mountains in Gila Co. It is a dense, bushy tree growing 45 to 60 ft high in the wild state, with a spreading crown and often lacking a central leader. The bark remains reddish, thin and smooth even on mature trees, and is shed in thin strips or plates (but becomes close on very old trees). The leaves are much greyer on the average than in C. arizonica, with conspicuous resin-secreting glands on the back. Some trees are strongly glaucous, especially when young and vigorous. The cones are usually larger than in C. arizonica and the seeds glaucous.
Many botanists have identified C. glabra with C. arizonica var. bonita Lemm., but C. B. Wolf has pointed out this variety differs in no respect from typical C. arizonica.
Owing to the confusion between the two species described above, the date of introduction of neither is known for certain. The seed sent by the Arnold Arboretum in 1882 is said to have been C. arizonica but may equally well have been C. glabra, which was described many years later. But the seed distributed by Purpus around 1890 was apparently collected in New Mexico, well within the range of C. arizonica. The trees cultivated in this country (most of which are probably C. glabra) are quite hardy and have reached heights of 60 to 75 ft and girths of 33⁄4 to 5 ft.
The beautiful form of the Arizona cypress so common in Italian gardens is usually known as C. arizonica conica (or pyramidalis). It is of narrowly conical habit, with blue-glaucous leaves. Although said to be tender in Central Europe it appears to be quite hardy in this country.
C. stephensonii C. B. Wolf – This rare species is allied to C. glabra but is less glandular and with smaller leaves (about 1⁄25 in. long). Confined to a small area in San Diego Co., California, and known as the Cuyamaca cypress.