NEW YORI 



TORREYA r^«'"' 



QAKDEN. 



September, 1909 

 Vol. 9 No. 9 



THE RUBBER PLANTS OF MEXICO* 



By H. H. Rusby 



Until within a few years, there was but a single known source 

 of commercial rubber in the entire republic of Mexico. Now 

 two species are contributing regular supplies, and a third, to be 

 specially considered here, is likely soon to become a very im- 

 portant factor in this industry. Mexico thus becomes one of the 

 most important of the world's ruljber-producing countries. 



That other sources remain to be developed is very certain, 

 since the fan)ilies Euphorbiaceae, Moraceae, and Apocynaceae, 

 Avhich comprise most of the rubber-yielding plants, are abun- 

 dantly represented in the Mexican flora. The same may be said 

 of the Sapotaceae, the family that yields gutta percha, chicle, and 

 balata. 



The first of the rubber-producing plants mentioned above is 

 Castilla clastica, the Central American rubber tree known also as 

 the Mexican rubber tree or "hule." in all but recent literature. 

 So al undant is this tree in one locality, that it and its railroad 

 station are known as El Hule. This tree also yields rubber in 

 tie Wtst Indian Islands. It is a near relative of the Ficus, 

 yielding the East Indian rubber, to which its product bears con- 

 siderable resemblance. On the other hand, it is not related to 

 the Hevea, which yields the superior Para or Amazon rubber 

 The Castilla becomes a large tree, some authors state up to six 

 feet in diameter, and lives to a great age. Owing to the destruc- 

 tive methods of collecting its latex, the exportation of Mexican 

 rubber declined from $160,000 in 1882-3 to $47,000 ten years 

 later, and the government was faced with what threatened to be 



[No. 8, Vol. 9, of ToRKEYA, Comprising pagcs 1 53-1 76, was issued August 3, 1909.] 

 * Abstract of a lecture delivered before the Torrey Club, February 9, 1909. Il- 

 lustrated with the aid of the Catherine McManes fund. 



177 



