198 



ORGANOGRAPHY. 



These varieties of arrangement have been already alluded to 

 when speaking of bracts ( page 182). 



On comparing the simple umbel with the capitulum, it will 

 be seen that it bears essentially the same relation to it, as the 

 raceme does to the spike. The compound umbel again may be 

 considered to bear the same relation to the simple umbel, as the 

 panicle does to the raceme. Or if we compare all the kinds of 

 inflorescence now described, we perceive that the chief difference 

 between them arises from the shortening or non-development 

 of different axes, and their varying lengths. 



Definite, Determinate, or Terminal Inflorescence. — 

 In this class of inflorescence the primary axis (as we have 

 seen) is arrested in its growth at an early age by the develop- 

 ment of a terminal flower-bud, and if the axis bears no other 

 flowers this is called a solitary terminal flower, and is the sim- 

 plest form of definite inflorescence. Examples may be seen in the 

 stemless Gentian {Gentiana acanlis) (Jiff. 405), and in the Wood 

 Anemone (Anemone nemorosa). "When other flowers are produced 



Fiff. 405. 



Fiff. 406. 



Fig. 405. Floral axis of a 

 species of Gentian {Genti- 

 ana acav.Uii), terminated 

 liy a solicary flower, below 



whicii are two bracts. 



Fig. 406. A plant of a 

 species of Ranunculus (Ra- 

 nunculus bulbusus). a', a'. 

 Primary axis terminated 

 by afully expanded flower 

 /'. a". Secondary axis, 

 wliicli is also terminated 

 by a flower/", not so fully 

 developed as/', a"'. Ter- 

 tiary axis terminated by 

 a flower-bud /'", which is 

 less developed than/' and 



