B. P. I.— 608. 



DIMORPHIC BRANCHES IN TROPICAL CROP 

 PLANTS: COTTON, COFFEE, CACAO, THE CEN- 

 TRAL AMERICAN RUBBER TREE, AND THE 



BANANA. 



INTRODUCTION. 



It has been known for a long- time that some species of plants have 

 two or more forms of branches, but such specializations have been 

 looked upon as botanical curiosities rather than as having practical 

 significance in agriculture. Several of the most important economic 

 species of the Tropics have now been found to have two or more 

 different and distinct kinds of branches regidarly present on every 

 normal plant. These difl'erences in the formation of the branches 

 are worthy of scientific study and have definite relations to agri- 

 cultural problems. 



The specializations of the branches of the tropical crop plants 

 are not mere inequalities of position and development like those 

 that commonly appear among the trees and shrubs of the temperate 

 regions. The differences do not arise merely from favorable or 

 unfavorable positions on the plant that might affect the supply of 

 food or the exposure to sunlight. The two kinds of branches are in 

 most cases so definitely different that they do not replace or serve as 

 substitutes for each other. The differences of the branches have 

 sometimes been recognized by individual planters of coffee or cacao, 

 but they have not received the study that the facts would warrant, 

 either in their scientific aspects or in relation to practical agricul- 

 tural applications. 



As the best means of describing the nature and extent of the diver- 

 sity of branches which exists in several of the more important tropical 

 crop plants, it seems desirable to bring together in one report the 

 facts of this kind which have been observed. The cvdtural sig^nifi- 

 cance of some of them is at once obvious and will show the desira- 

 bility of further study in this class of phenomena. That much more 

 information of this kind remains to be discovered seems strongly to 

 be indicated by the fact that a definite diversity of branches has been 

 found in all of the principal tropical crop plants to which attention 

 has been directed with this idea in mind. 



198 7 



