ERICACES. SILVA OF NORTH AMERICA. 127 
ARBUTUS ARIZONICA. 
Madrofta. 
Ovary glabrous, conspicuously porulose. Leaves lanceolate or rarely narrowly 
oblong. 
Arbutus Arizonica, Sargent, Garden and Forest, iv. 317, Arbutus Xalapensis, Sargent, Forest Trees N. Am. 10th 
f. 54 (1891). Census U. S. ix. 97 (not Humboldt, Bonpland & Kunth) 
Arbutus Menziesii, Rothrock, Wheeler’s Rep. vi. 25, 183 (1884). 
(not Pursh) (1878). — Gray, Brewer & Watson Bot. Cal. Arbutus Xalapensis, var. Arizonica, Gray, Syn. Fl. N. 
i, 452 (in part) ; Syn. Fl. N. Am. ii. 27 (in part). Am. ed. 2, i. pt. ii. 396 (1886). 
A tree, forty or fifty feet in height, with a tall straight trunk eighteen to twenty-four inches in 
diameter, stout spreading branches which form a rather compact round-topped head, and thick tortuous 
divergent branchlets. The bark of the trunk, which varies from one third to one half of an inch in 
thickness and is irregularly broken by longitudinal furrows, is divided into square appressed plate-like 
scales, and is light gray or nearly white and faintly tinged with red on the surface. The bark of young 
stems and of the branches is thin, smooth, and dark red, and exfoliates in large thin scales. The 
branchlets, when they first appear, are reddish brown and more or less pubescent, or are light purple 
and pilose with a glaucous bloom, and by the end of their first season are covered with bright red bark 
which separates freely into thin irregularly shaped more or less persistent scales. The leaves are 
lanceolate or rarely oblong, acute or rounded and apiculate at the apex, and wedge-shaped or occasion- 
ally rounded at the base, with thickened entire or rarely denticulate margins; when they unfold they 
are membranaceous, tinged with red, and slightly puberulous especially on the petioles and margins; 
and at maturity they are thin, firm, and rigid, glabrous, light green on the upper surface, pale on the 
lower surface, an inch and a half to three inches long and half an inch to an inch wide, with slender 
yellow midribs and obscure reticulate veinlets, and are borne on slender petioles often an inch in length ; 
they appear in May and after the summer rains in September, and remain for at least one year on the 
branches. The flowers, which expand in May, are borne on short stout hairy pedicels developed from 
the axils of conspicuous ovate rounded scarious bracts, and are collected in rather loose terminal clusters 
two or two and a half inches in length and breadth, their lower branches from the axils of the upper 
leaves ; they are a quarter of an inch long, with scarious calyx-lobes, ovate white corollas often much 
contracted in the middle, conspicuously lobed disks, and glabrous porulose ovaries. The fruit ripens 
in October and November, and is drupaceous, globose or oblong, dark orange-red, porulose, with thin 
sweetish flesh, a papery five-celled usually incompletely developed stone, and compressed puberulous 
seeds. 
Arbutus Arizonica inhabits the Santa Catalina and the Santa Rita Mountains of southern Arizona, 
where, associated with Quercus grisea, Quercus Emory’, Quercus chrysolepis, and Pinus ponderosa, 
it grows on dry gravelly benches at elevations of from six to eight thousand feet above the sea; and 
ranges southward along the Sierra Madre of Chihuahua.’ 
The wood of Arbutus Arizonica is heavy and close-grained although soft and brittle ; it contains 
numerous obscure medullary rays, and is hght brown tinged with red, with lighter colored sapwood com- 
posed of thirty to forty layers of annual growth. The specific gravity of the absolutely dry wood is 
0.7099, a cubic foot weighing 44.24 pounds. 
1 Here it was found at an elevation of eight thousand feet by Mr. C. G. Pringle in 1885. 
