CONCLUSIONS. 



55 



The relations between the positions and the fnnctions of the 

 branches of the four woody pLants are summarized as follows : 



Summary of the classification of branches. 



CONCLUSIONS. 



Definite dimorphism of branches exists in at least five important 

 tropical crop plants— cotton, coffee, cacao, the Central American 

 rubber tree (Castilla), and the banana. Each normal plant pro- 

 duces two kinds of branches, with regular differences of form and 

 function. 



The factor of branch dimorphism must be taken into account in 

 the scientific study of the structure and habits of all these plants, 

 as well as in the breeding and adaptation of varieties. Systems of 

 cultivation and pruning must likewise be planned with reference 

 to the habits of branching. 



In each species there is a definite relation between the functions 

 of the branches and their positions or places of origin on the inter- 

 nodes, but there is no general relation of position to function that 

 applies to all the species, or even to any two of them. It is neces- 

 sary to consider each plant separately in order to understand the 

 agricultural importance of the dimorphism of the branches. 



In the cotton plant the branches that arise in the axillary posi- 

 tion have vegetative functions only, like the main stalk. The 

 branches that produce the flowers and fruit are extra-axillary ; that 

 is, they arise at one side of the axillary branch or bud. Branches 

 with the vegetative form and functions may replace the fruiting 

 branches, in the extra-axillary position, but no normal fruiting 

 branches develop in the axillary position. 



The definite differentiation of the two kinds of branches represents 

 a normal condition in all the types of cotton that have been studied 



198 



