INFLORESCENCE. 



125 



sessile in the axils, the cluster becomes a spike, of which 

 the common Plantain and the Mullein furnish good 

 examples. The catkins of the Willow (Figs. 68 and 69) 

 and Birch and the spadix of the Indian Turnip (Figs. 

 96 and 97) are also spikes, the former having scaly 

 bracts and the latter a fleshy axis. If you suppose the 



Fig. 170. 



internodes of a spike to be suppressed so that the flowers 

 are densely crowded, you will have a head, of which 

 Clover and Button-bush supply instances. If the lower 

 pedicels of a raceme are considerably longer than the 



Fig. 170. Plan of the simple corymb. 

 Fig. 171. Compound raceme. (Gray.) 



