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Castillo, is able to live through the sapling and pole stages without 

 protection against wind. 



Another way in which Cast ilia gets protection from neighbour- 

 ing trees is that these give shelter to the ground, retain moisture, 

 and prevent the soil from cracking. Castilla is very sensitive to 

 these influences, as its roots do not develop properly in hard- 

 baked ground. 



Castilla does not, on the other hand, develop well in shade. 

 It grows very slender, with a weak trunk and an undeveloped 

 crown. The tree needs plenty of light for its foliage and it is 

 only where the Castilla tree has room enough to spread its 

 branches and expose its foliage to the rays of the sun that it can 

 successfully maintain its position in the struggle for space and 

 light. 



In districts where a distinct dry season prevails, Castilla is 

 pronouncedly deciduous and drops its leaves at that period of the 

 year, while in a humid region the shedding of leaves goes on all 

 the year round. On the Pacific side of Sierra Madre in Mexico, 

 the dry season lasts from January to May, and the rubber tree 

 begins to shed its leaves with the advent of this season, and 

 towards its close the trees are almost destitute of foliage. 



It is generally stated that Castilla does not flower and set 

 fruit before it has reached an age of about five years. Another 

 statement is that flowering commences when the tree begins to 

 develop permanent branches. My observations show that if 

 Castilla is grown on good soil in a suitable climate, and if the 

 development has been normal, the tree will flower in its third 

 year, whether it has permanent branches or not. I have seen 

 many two years old trees with flowers and fruit, but I would 

 consider this premature, and indicating that something is wrong 

 with the tree. 



The season of flowering is from February to the beginnir g 

 of May in the Zacualpa district in Mexico, and in Western 

 Guatemala. The earliest fruits begin to ripen in May and ripe 

 seeds can be had until August. 



The flowers are unisexual, but both sexes occur on the same 

 tree. I have often heard it stated by planters and others, that 

 there are two distinct trees, the male and female. It is also said, 

 and generally believed, that the " male trees" do not produce 

 latex as well as the " female." In my experience all the older 

 trees carry both male or staminate and female or pistillate flowers. 

 While the trees are young they often have only staminate flowers 

 but after reaching a more mature age both sexes are present. I 

 think we can safely abandon the idea that some trees are male and 

 therefore no " milkers," while others are female and good milk 

 producers. Such an analogy is rather far fetched and has a 

 strong flavour of ignorance. 



I have found trees on which the female flowers have been 

 sterile on account of insufficient development of the ovary. Such 

 trees naturally do not produce fruit. Whether there are any 

 permanently sterile trees is a question yet to be investigated. 



