16 BULLETIN" 460, U. S. DEPARTMENT OF AGRICULTURE. 



Pinus cembroides was discovered 1 about 1830 by the Belgian ex- 

 plorer Karwinsky in the southern part of the State of Mexico. 2 It 

 remained unknown in the United States until 1882, when it was 

 found on the Santa Catalina Mountains, Arizona, by Mr. C. G. Prin- 

 gle, 3 an American botanist and explorer. Pinus cembroides, the first 

 technical name applied to the Mexican pinon, was published in 1832. 4 



DISTINGUISHING CHARACTERISTICS. 



Mexican pinon is ordinarily a very short-trunked tree from 12 to 

 25 feet high and from 7 to 12 inches in diameter. Such trees have 

 a clear trunk of from 3 to 8 feet. Trees growing in protected places 

 reach a height of from 35 to 50 or more feet, with 15 to 18 feet of 

 clear trunk and a diameter of from 12 to 14 inches. The crowns 

 of young trees are compact and conical, the branches being more 

 or less upright; the crowns of old trees are wide and rounded, the 

 lateral crown branches being mostly horizontal. On large trunks 

 the bark is pale reddish brown, distinctly scaly, thin (not over half of 

 an inch thick), and divided by very shallow furrows and ridges, 

 which are not connected by smaller side ridges as in the case of other 

 nut pines. 



The foliage, especially on young trees, is a deep bluish green, that 

 of each season's growth remaining on the branches about 4 years, 

 though most of it falls during the third or fourth season. The 

 number of leaves borne in a bundle is commonly 2 or 3 (rarely and 

 exceptionally 1, 4, and 5). They are from about 1 to 2 inches long, 

 acutely pointed, strongly incurved, and smooth on the margins. A 



iFide Sargent, Silva, XI, 48. 1897. 



2 According to Elwes and Henry (The Trees of Great Britain and Ireland, V. 1059. 

 1910) Pinus cembroides was introduced into England in 1830. (If this date be correct, 

 it is probable that Karwinsky, the discoverer of the tree, found it in Mexico at an earlier 

 date than "about 1830." the year indicated by Prof. Sargent. 1. c). They state that in 

 1908 trees of this species planted in England reached a height of 25 to 33 feet. It is 

 said to have been introduced into Europe by Hartweg in 1846 (fide Sargent, 1. e.) and is 

 now cultivated for ornament in southern Europe. 



3 Sargent, 1. c. 



i Since the first publication of this tree as a species in 1832 botanists have generally 

 held it to be distinct from the other southwestern nut pines, the only names applied to it, 

 until quite recently, being P. llaveana Schl. and P. osteoperma Engelm., now relegated to 

 synonymy. In 1907, however, a German botanist (Voss, Mitt. Deutsch. Dend. Fresell., 

 XVI, 95, 1907) pronounced it to be related to the simple-leaf pine and the two-leaf pinon, 

 which he designates as P. cembroides var. monophylla and P. cciubroides var. edulis, to 

 which he has also added our southern California four-leaf pine (P. parryana) as P. 

 cembroides var. parryana. This writer considers the cones of all of these pifions essen- 

 tially alike ; and, owing also to the inconstancy in the number of leaves borne by each, 

 he is unable to separate them satisfactorily as species. The present writer, however, 

 prefers to maintain the Mexican piiion as a distinct species: (1) because, in the main, 

 our forms of the tree have a reasonably constant number of leaves in each fascicle: (2i 

 because the cones are distinguishable in size and other characteristics, the seeds also hav- 

 ing the same general distinctions; (3) because the bark is distinctly scaly and only 

 slightly ridged, that of the other nut pines being markedly ridged; (4i because the num- 

 ber of seed-leaves is greater than in any other nut pine ; (5) and, lastly, because the wood 

 has characteristics which distinguish it. 



