RACEMOSE INFLORESCENCES 53 



(iii.) A catkin (fig. 131, ^) is an inflorescence 

 of inconspicuous sessile, staminate or 

 carpellary, flowers : after flowering it 

 usually drops off as a whole. It is 

 racemose in type, but in the axils of 

 the bracts cymes may occur in place of 

 single flowers, in which case the catkin 

 is a compound inflorescence. 

 (b) The flowers are set close together on a shortened main 

 axis. 



(a) The flowers are stalked = Umbel. 



The umbel exhibits a considerable number 

 of flowers springing from the shortened 

 terminal . part of the axis. Usually there is 

 a terminal flower in the inflorescence. An 

 umbel is essentially a condensed simple 

 raceme (fig. 74). 

 Example — Ivy. 

 (p) The flowers are not stalked (fig- 75) = Capitulum. 

 The shortened terminal part of the main 

 axis bears a number of closely - clustered 

 stalkless flowers, forming a capitulum or 

 head. 



Examples — Sunflower ( fig. 208 ), 

 Dandelion (fig. 253), Daisy. 



II. Compound Racemose Inflorescences. — The main axis of 

 the inflorescence does not itself bear flowers, but has lateral 

 branches which are inflorescences. The main type of branch- 

 ing of the inflorescence is termed the main or primary inflor- 

 escence, and the lateral inflorescences are styled the secondary 

 inflorescences, etc. 



(a) The main axis is elongated, so that its branches are 

 separated by distinct internodes. 



(a) The main axis bears lateral racemose inflor- 

 escences with stalked flowers (fig. 69) 



= Panicle. 

 (p) The main axis bears somewhat shortened lateral 

 inflorescences which are spikes (fig. 231) 



= Compound Spike. 

 Example — Wheat. 



