conifer*. SILVA OF NORTH AMERICA, 75 



PINUS ARIZONICA. 



Yellow Pine. 



Leaves in 5-leaved clusters, stout, rigid, from 5 to 7 inches in length. Cones oval, 

 from 2 to 2J inches long, their scales armed with slender recurved spines. 



Pinus Arizonica, Engelmann, Rothrock Wheeler's Rep. vi. 192. — Mayr, Wald. Nordam. 239, t. 8, f. — Beissner, 



260 (1878) ; Trans. St. Louis Acad. iv. 181 ; Rot. Go- Handb. Nadelh. 260. — Masters, Jour. R. Hort. Soc. 



zette, vii. 4. — Hemsley, Rot. Riol. Am. Cent. iii. 186. — xiv. 225. — Koehne, Deutsche Dendr. 34. — Lemmon, 



Sargent, Forest Trees N. Am. 10th Census U. S. ix. West-American Cone-Rearers, 35. 



A tree, from eighty to one hundred feet in height, with a tall straight massive trunk from three to 

 four feet in diameter, and stout spreading branches forming an irregular open round-topped or narrow 

 pyramidal head. The bark on young trunks is dark brown or almost black and deeply furrowed, and 

 on fully grown trees it is from an inch and a half to two inches in thickness and divided into large 

 unequally shaped plates separating on the surface into thin closely appressed light cinnamon-red scales. 

 The branchlets are stout and dark orange-brown when they first appear, growing lighter in their 

 second and third years, and then dark gray-brown. The branch-buds are ovate, acute, nearly half an 

 inch long, and covered by loosely imbricated dark chestnut-brown scales with pale fringed margins, 

 which continue for many years to roughen the branches with their thickened bases. The sheaths of 

 the leaf -clusters, which at first are loose and bright chestnut-brown and from three quarters of an inch 

 to an inch in length, soon become thick and firm, pale brown below, silvery above, and about half an 

 inch long by the falling of the inner bud-scales, and are persistent. The leaves are borne in clusters of 

 five and are stout, rigid, acute with short callous tips, closely serrulate, dark green, stomatiferous on their 

 three faces, and from five to seven inches in length ; they contain two flbro-vascular bundles and three 

 parenchymatous resin passages, one in each of the angles, surrounded by strengthening cells, which also 

 occur under the epidermis mostly in a single layer ; they form dense tufts at the ends of the branches 

 and appear to fall during their third year. The staminate flowers are produced in short compact spikes 

 and are oval and from three quarters of an inch to an inch in length and about a quarter of an inch 

 thick, with dark purple anthers terminating in orbicular denticulate crests, and are surrounded by an 

 involucre of about twelve broadly ovate acute firm dark chestnut-brown lustrous bracts. The pistillate 

 flowers are subterminal and usually in pairs on stout peduncles covered by ovate acute chestnut-brown 

 bracts, and are about one third of an inch in length, with long-pointed dark purple reflexed scales. The 

 cones remain erect and do not enlarge much during their first season, but when the flowers open the 

 following spring they are horizontal, an inch and a half long and nearly an inch wide, with prominent 

 strongly incurved tips to their scales ; when fully grown in the autumn they are oval, from two to two 

 and a half inches long and an inch and a half wide, with thin slightly concave scales rounded or pointed 

 at the apex, the apophyses being transversely keeled and much thickened into central knobs terminated 

 by stout umbos armed with slender recurved spines, and much recurved on the small lower scales ; 

 when the cones are open in the autumn the exposed portions of the scales are light red-brown and 

 lustrous and the remainder dull red-brown on the upper side and dark purple on the lower. The 

 seeds are an eighth of an inch long, full and rounded below, slightly compressed toward the apex, with 

 a thick coat produced above into a narrow margin ; their wings are broadest above the middle, about 

 a third of an inch long, nearly a quarter of an inch wide, thin and light chestnut-brown. 



In the United States Pinus Arizonica inhabits the cool high slopes and the sides of canons of the 



