8 VEGETABLE ORGANOGRAPHY. 



It usually happens, especially in erect stems, that the 

 upper leaves, even when they do not bear flowers, are 

 smaller, and have their internodes shorter than the 

 lower ones, which results from their slower develop- 

 ment, and their receiving less nourishment. This 

 double effect is greatly augmented if these same upper 

 leaves bear a flower in their axil, probably because this 

 flower attracts a part of the nourishment, which would 

 otherwise have been employed either in making the 

 leaf larger, or elongating the internode ; in this case 

 the leaf is called the floral one, or bract, and the top of 

 the stem or branch, thus organized, receives the name 

 of the Terminal Raceme, or Spike. It seems, in fact, 

 to terminate the stem, but it is only formed of axillary 

 flowers, and the stem only ceases to elongate by the 

 exhaustion which it suffers in developing the flowers 

 and nourishing the seeds ; it then terminates in a point 

 by the simultaneous abortion of the flowers and bracts. 

 It is well known that by much nourishment these 

 branches can be made to elongate beyond their ordinary 

 dimensions ; sometimes they are naturally prolonged 

 in an unusual manner. Thus in the Pine-apple and 

 Eucomis, the axis of the stem is prolonged at the apex, 

 and it ceases to bear flowers; then the leaves which 

 were small and membranous where they had axillary 

 flowers, become large and truly foliaceous here where they 

 have none : it is this which forms the crown which sur- 

 mounts the spike of the Pine-apple and the raceme of 

 Eucomis. An analogous phenomenon is met with in 

 Galiistemon, and some other Myrtaceae of New Holland; 

 the axis of the spike is prolonged at the apex, and 

 forms' above the inflorescence, a true branch with leaves : 

 tins phenomenon also accidentally happens in some 

 cones, the axis of which is prolonged into a leafy 

 branch (PI. 16, fig. 4). It is to the inflorescence similar 



