

COMPARISON WITH THE TRUMPET TREE. 29 



conditions than their wild relatives. It is easy, however, to overlook 

 some essential requirement of a new culture, and it is a distinct advan- 

 tage to understand as thoroughly as possible the habits of a wild plant 

 which it is desired to domesticate. The tamarack and the cypress, for 

 example, are in nature confined to swamps, but they grow as well or 

 better when planted on dry ground. The difficulty is that without 

 human assistance they are unable to establish themselves on dry ground. 

 Similarly, it has been inferred regarding Castilla that it is a shade- 

 loving plant because it is found wild only in the forest. It is known, 

 however, that it is thus limited in nature because the seed is so thin- 

 skinned and short-lived that there is no possibility of its surviving 

 exposure to the open sun on dry ground, and it is abundantly proved 

 that young trees planted by man in the open are able not only to resist 

 exposure to the sun, but that they actually thrive better than those 

 planted by natural agencies in the forest. This fact should be sufficient 

 for the purposes of practical agriculture, unless there are reasons for 

 believing that more rubber can be produced in the forest. This is 

 sometimes argued on the ground that Castilla is a native of dense 

 forests and can not be expected to }deld as much rubber under other 

 conditions. If, however, it is true that Castilla, or at least Castilla 

 elastica, is not a forest tree in any extreme sense of the words other 

 reasons will be needed to justify shade planting; 



THE RUBBER TREE AND THE TRUMPET TREE. 



Castilla is a relative of the trumpet tree (Cecropia) and has a similar 

 place in the general economy of nature. Cecropia is widely distrib- 

 uted in the Tropics, but is not looked upon as a true forest tree. It is 

 what might be termed a tree weed. It shoots up with great rapidity, 

 and is able for a time to keep ahead of the other vegetation which in 

 most tropical countries promptly takes possession of land neglected 

 after cultivation. Cecropia is thus one of many plants which have 

 received indirect advantage from man's agricultural operations, and 

 it is seldom found in great abundance except where larger growth 

 has been cleared away. In the undisturbed forest it can not withstand 

 the competition of the long-lived hard-wood trees and is found but 

 sparingly, being limited to openings made by fallen timber, forest 

 fires, changes of river channels, and other accidents which give it an 

 opportunity for growth. The same appears to be even more true of 

 Castilla. Scattering trees are probably to be found at greater or 

 smaller intervals throughout the forests of low elevations, but there 

 seem to be no indications that they exist in numbers except in forests 

 of rather open growth, such as those which produce also the large 

 palms of the genus Attalea, and which there is reason to believe do 

 not represent a truly primeval condition or one of complete foresta- 

 tion, though the last clearing may have taken place centuries ago. 



