86 



DESCRIPTIVE BOTANY. 



PART I. 





oak, the peculiar spike in which the flowers are 

 arranged is termed a " catkin." In the 

 tribe to which the common arum belongs 

 (Aroidea-^), the fleshy mass which forms 

 the axis round which the flowers are 

 aggregated in a spike, is termed the "spa- 

 dix" (fig. 88. 6). The small spikes in 

 which the flowers of grasses are aggre- 

 gated, are termed "spikelets" (fig, 95. 

 c) ; and these, again, are arranged round 

 a common axis into a compound spike. 



In this kind of inflorescence, those 

 secondary buds which are seated lowest 

 on the main axis are the first formed, 

 and their flowers expand the earliest. 

 As these are also the outermost, with 

 respect to the terminal bud, the order 

 of expansion is from the circumference 

 inwards, or contrary to that which takes 

 place in the terminal inflorescence ; and hence 

 has been called the " Centripetal inflorescence." 



When the leaves are ver- 

 ticillate, the secondary buds 

 may either become flowers, or 

 produce branches, on which 

 buds of a lower order be- 

 come flower-buds. This kind 

 of inflorescence is generally 

 called " whorled," and is either 

 simpleor compound (fig.83.). 



(90.) Modifications of 

 Inflorescence. It will be 

 seen from what has been 

 said, that the application of 

 the term " inflorescence," is 

 as indefinite as the use of 

 the word " organ," which 

 we equally employ, to signify 

 the several parts of a plant, as well as the subordinate 



