THE CENTRAL AMERICAN RUBBER TREE 213 



These Vcarieties of Castilloa have been carefully studied 

 recently by several botanists, notably by Cook and 

 Pittier of the United States Department of Agriculture, 

 with the result that a number of them have been de- 

 scribed as separate species. Pittier, the most recent 

 mvestigator, is of opinion that the foUowmg ten species 

 of Castilloa may be provisionally recognised : C. elastica, 

 Lew ; C costaricana, Liebm. ; C. fallax, Cook ; C. lactiflua, 

 Cook; C. mcoyensis, Cook; C. paTiamensis, Cook- C 

 gmitemalensis, Pittier ; C. daguensis, Pittier ; C. australis, 

 Hemsl. ; and C. Ulei, Warb. 



The first eight species are natives of Central America • 

 C australis occurs m Peru, and C. Ulei in the Amazon 

 vaUey. In addition to these forms there is another 

 Central American species described by Hemsley as C. 

 Tunu, upon which Pittier is at present unable to pro- 

 nounce a definite opinion. 



Pittier states that the ten forms mentioned above 

 are perfectly distmct and characteristic, but he admits 

 that fmther study may reduce some of them to the 

 position of subspecies or varieties. 



The existence of these different species or well-marked 

 varieties of CastiUoa, which require different climatic 

 conditions and fiurnish varying amounts of rubber, is a 

 pomt of considerable importance to planters, and care 

 should be taken to select for cultivation the particular 

 form of tree most suited to the local conditions of clmiate 

 and soil. Pittier has stated that for semi-arid districts 

 with well-characterised dry and rainy seasons he would 

 recommend C. lactiflvu of the Soconusco district of the 

 State of Chiapas m Southern Mexico ; C. nicoyensis from 

 the dry Pacific slopes of the Nicoya Penmsula in Costa 

 Rica ; and probably C. panamensis from Panama. For 

 districts where ram predommates, he considers that C. 

 costaricana from the humid Atlantic slopes of Costa 

 Rica and C. elastica are the most suitable. Experiments 

 with the different varieties are bemg conducted m ^Mexico 

 m order to determine their relative value as sources of 

 rubber. 



In the followmg account it will be convenient to regard 

 the name Castilloa elastica as including the different 

 forms of Castilloa trees occmrmg in Central America. 



Botanical Characters.— Cas^zY^oa ekisiica is a large tree 



