44 



DIMOEPHIC BRANCHES IN TROPICAL CROP PLANTS. 



The names of the two kinds of offshoots allude to differences in the 

 size and shape of the leaves. The broad-leaved suckers begin near 

 the ground to produce leaf blades of the same general form as those 



of the adult plant (fig. 8). The 

 sword suckers produce at first only 

 small narrow blades that by their 

 shape suggest the name (fig. 9). 

 The basal, sheathing parts of the 

 leaves that form the so-called 

 " trunk " of the banana plant are 

 much larger in the sword suckers, 

 and this renders the reduction of 

 the blade of the leaf a more evi- 

 dent specialization. 



Possibly the dimorphism of the 

 branches is not as definite in the 

 banana as in the woody plants 

 previously considered. Though 

 no connecting stages betAveen the 

 two kinds of branches were no- 

 ticed in the rootstocks that were 

 dug out and examined, it may be 

 that intermediate conditions will 

 be found occasionally, as in Indian 

 corn. The intermediate joints of 

 corn idants, betw^een the ears and 

 the suckers, seldom develop 

 branches, but when such branches 

 are developed they are intermedi- 

 ate in form, as well as in position. 

 The differences in the develop- 

 ment of the leaves call attention 

 at once to the fact that the two 

 kinds of banana suckers stand in 

 different relations to the parent 

 plant. The broad-leaved suckers, 

 with their relatively large, ex- 

 panded leaves, are able from the 

 first to elaborate a larger part of 

 the nourishment they require than 

 are the sword suckers, yet in spite of this apparent advantage 

 the broad-leaved suckers are of much slower growth. It is evident 

 from this fact that the sword suckers stand in a different relation to 



Fig. 9. — Sword suckers of the commer- 

 cial banana, used in setting out planta- 

 tions in Costa Rica. (Greatly reduced.) 



198 



