52 SHADE IN COFFEE CULTURE. 



or cacao to be cultivated would be very detrimental to the rubber, while elsewhere 

 the rubber would be a drawback to the other crop, without furnishing any compen- 

 sating advantage. The present trend of opinion is that the Castilloa rubber can be 

 looked upon only as a tree requiring essentially tropical forest conditions, outside of 

 which it may sometimes thrive, but refuses to produce rubber in quantities sufficient 

 to make its culture profitable. The reason why trees standing apart in orchard form 

 are not productive has not yet been demonstrated, though several suggestions have 

 been made. It is well known that the bark of trees standing in the open is of quite 

 different texture from that which grows on the same species in the forest, where the 

 air is constantly moist and winds and sunlight are excluded. The bark of Castilloa 

 is said to become much thicker and more corky in exposed trees, and it has been 

 thought that this might interfere with the flow of milk when the trees are tapped. 

 It is easy to see how this might be the case with a small cut, but from the large 

 gashes usually employed the flow would scarcely be impeded by the nature of the 

 outside layers of the bark. A more probable cause of difficulty in securing rubber 

 from cultivated trees is the fact that in the forest the trunk of Castilloa becomes tall 

 and columnar, being much larger in proportion to the top than when grown in the 

 open. This may easily affect the pressure relations of the inclosed liquids, and may 

 forbid the employment of other than forest culture while the present methods of 

 harvesting the rubber are in use. A third possibility is that the milk of exposed trees 

 is really thicker and less fluid than in the forest. Finally, the drier atmosphere of 

 open orchards may have an influence in causing coagulation and impeding the flow 

 of the milk. 



In the State of Oaxaca plantations are now being set out in which rubber is alternated 

 with coffee, as already noted. In this instance the rubber is not, however, being 

 used to shade the coffee, but both rubber and coffee are planted in the thinned out 

 natural forest. Unless the circumstances are exceptional this method is likely to offer 

 many difficulties, in that seedlings and sprouts from the stumps and roots of the forest 

 species will make rapid and repeated growth and require frequent cleaning. The 

 coffee and rubber, on the other hand, may grow much more slowly than in open, 

 thoroughly cultivated land. The advantages of the arrangement are thus not obvious, 

 though local conditions may be found to justify it. 



According to Martinez, the use of the hule as shade for cacao was abandoned in the 

 State of Tabasco, Mexico, because the young trees were found to be delicate and to 

 require the same care as the young cacao. 



Castor bean. (See Ricinus communis.) 



Casuarina equisetifolia. 



Common name. — Pina de Santo Domingo (Porto Rico). 

 Suggested by Morris for windbreaks for cacao plantations in Jamaica because of 

 its rapid growth, resistance to wind, and useful timber. Its loose and open habit and 

 slender branches afford, however, but the slightest resistance to the wind. As is 

 the case with Eucalyptus, nothing grows under Casuarina. 



Cay vong nem (Philippine Is.). (See Erythrina indica.) 

 Ceara rubber. (See Manihot glaziovii.) 

 Cedrela microcarpa. 



This species is said to be used with C. toona in the Coorg district of western 

 Hindustan. 



Cedrela odorata. West Indian Cedar. 



Common names. — Acajou amer and Acajou du pays (Guadeloupe); Spanish 

 Cedar; West Indian Cedar. 

 Family Meliaceae. A fine tree, native in the West Indies. It has been planted as 

 a shade tree for cacao in Guadeloupe, where it is said to resist parasites better than 



