COMPAEISONS OP SYSTEMS AND TYPES OF BEANCHES. 49 



and adventitious. This compels us to infer that branches which 

 do not come from the axils of the leaves must be regarded as adventi- 

 tious, or to some extent irregular and abnormal. 



It may be that the present series of facts of dimorphism will 

 incline botanists as well as planters to take into account the normal 

 and regular existence of branches which are neither truh^ axillary 

 nor truly adventitious. It is as impossible to understand the habits 

 of growth of the plants from the botanical standpoint as it is to find 

 correct principles of cultivation and pruning without seeing that 

 the same plant can produce two or more kinds of branch organs 

 essentially distinct from each other in position, form, and function. 



The different systems of branching have evidently been specialized 

 on independent lines that could hardly be described on the basis of 

 the usual classification of branches into two general classes — axillary 

 and adventitious. There should be no implication that extra-axillary 

 buds are of necessity adventitious, or that extra-axillary or adven- 

 titious buds are less important in anj'^ particular plant than axillary 

 buds. There are no general relations between the position and the 

 function, nor between the position and the time of appearance, nor 

 yet between the time of appearance and the function. There are no 

 general principles that apply to the dimorphic branches of all the 

 different plants, nor do any two of them fully agree. 



The extra-axillary branches of the coffee have the fruit-bearing 

 functions of the axillary branches of Castilla, while the axillary 

 uprights of coffee correspond functionally to extra-axillary uprights 

 of Castilla. The axillary branches of Castilla must be considered 

 as more definitely limited on the vegetative side than the extra- 

 axillary branches of the other plants, in view of their temporary 

 nature. 



The specializations shown in the branches of the cotton plant are 

 in some respects quite the opposite of those of the Central American 

 rubber tree. The flowers and fruit of the cotton plant are borne on 

 extra-axillary branches, those of Castilla on the axillary branches. 

 The vegetative limbs of Castilla are all extra-axillary, while those 

 of cotton are axillary. The axillary or fertile branches of Castilla 

 are temporary, while the extra-axillary serve as permanent divisions 

 of the main stem." 



Coffee agrees better with cotton than with Castilla, since it is the 

 axillary buds Avhich give rise to the permanent, upright shoots. The 

 extra-axillary branches of cotton and coffee are also alike in the bear- 

 ing of fruit. Though extra-axillary in position they can hardly be 

 called adventitious. Indeed, they are less adventitious than the axillary 

 branches, for they are developed with far greater regularity. Extra- 

 axillary buds in cotton and coffee seem to lack the power of remaining 

 58884°— Bui. 198—11 4 



