28 BULLETIN 327, U. S. DEPARTMENT OF AGRICULTURE. 



cone scales and of the bracts 1 (compare Pis. XI, a, and XIV, a). 

 The book name "Arizona cork fir " has not become established, and 

 can well be replaced now by the shorter and more fitting name " cork 

 fir." "Arizona cork fir" is a name particularly inappropriate, be- 

 cause the tree is not confined in its range to Arizona. 



Ab^es arizonica was first discovered in 1896 by Dr. C. Hart Mer- 

 riam 2 on a high peak of San Francisco Mountain, Ariz. Since 

 then its range has been considerably extended in Arizona, and the 

 tree is now known to occur in New Mexico and southern Colorado 

 (Map No. 7). Future explorations are likely to extend this range 

 still farther in the southern Rocky Mountain region. 



DISTINGUISHING CHARACTERISTICS. 



As now known, cork fir attains a height of from 50 to 75 feet and 

 a diameter of from 12 to about 20 inches. Doubtless larger trees 

 occur. The trunk and crown forms are practically the same as in 

 the alpine fir. The yellowish-white or ashy, soft, corky trunk bark 

 (PL XV) of Abies arizonica at once distinguishes this tree from A. 

 lasiocarpa (PI. XIII) and from all other associates. The form and 

 habit of the leaves of the cork fir and Alpine fir are so similar in 

 general appearance that the two trees can not be distinguished by 

 their foliage. The cones (compare Pis. XI and XIV) of the two 

 trees are more or less dissimilar in form and size, but alike in color, 

 and both ripen at about the same time in September. The cone 

 scales of A. arizonica are, however, generally of a distinctly different 

 form (PI. XIV, a) from those of A. lasiocarpa (PL XI, a), while 



1 Writers who hold this tree to be a form only of the alpine fir seem not to give due 

 weight to the fairly constant difference in the form of the cone scales and bracts of the 

 cork-barked tree as compared with the shape of cone scale and bracts peculiar to the 

 alpine fir. The specific importance of the distinctly corky bark of Abies arizonica is also 

 denied by citing the occurrence of similar corky bark of southern Rocky Mountain forms 

 of white fir and of Douglas fir, and, furthermore, that corky-barked Alpine fir trees occur 

 far north and west of the present range claimed for Abies arizonica. While it is true in 

 general that the bark of many trees is so variable in character as not to afford a reliable 

 specific distinction, it is true nevertheless that a large number of trees have barks of very 

 distinct character. I have often seen Douglas fir and white fir in the Southwest, espe- 

 cially in dry, exposed situations, with corky bark, but not of the distinctly corky nature 

 of bark produced by Abies arizonica. I believe, however, that the corky bark of Douglas 

 fir and white fir is the result of arid conditions, which appear to affect young trees, the 

 corky bark so formed later becoming harder as these trees grow older. In the case, how- 

 ever, of A. arizonica, I do not know that the bark ever becomes harder or less corky. 

 Taking into account the fact that the cone scales and bracts of A. arizonica are usually 

 distinct in form from those produced by A. lasiocarpa, I am confident that the occurrence 

 of corky-barked Douglas fir and white fir trees is a circumstantial coincidence rather than 

 proof that A. arizonica is only a corky-barked form of A. lasiocarpa. I have never seen 

 the cork-barked alpine fir trees reported as occurring north of Colorado and elsewhere 

 outside of the present recorded range of A. arizonica. I should be inclined to believe,- 

 however, that these trees represent Dr. Merriam's Abies arizonica, rather than corky- 

 barked forms of A. lasiocarpa. Otherwise I am unable to satisfactorily explain why, in 

 Colorado, New Mexico, and Arizona, A. arizonica occurs side by side with the distinctly 

 hard-barked A. lasiocarpa, a fact which would seem to indicate that the cork-barked tree 

 is inherently different from its associate. 



2 Proc. Biol. Soc. Washington, X, 115, figs. 24, 25, 1896. 



