114 



MANUAL OF BOTANY 



1. The Compound Spike. — An instance of this is seen in the 

 Wheat and certain other grasses. A variety of it is sometimes naet 

 with, as in the Oat, where the main inflorescence is of the form 

 of a panicle, but the ultimate branches are spikelets. 



m. The Compound Spadix. — This form is seldom met with, 

 as the spadix does not often branch. Instances may be seen in 

 the Palms (fig. 218). 



B. Forms possessing a Shortened Primary Axis. 



Of these we distinguish the simple and the compound Umbel. 



n. The TJmhel. — When the primary axis is shortened, and 

 gives off from its apex a number of secondary axes or pedicels of 

 nearly equal length, each bearing a flower, an umbel is formed 



Fig. 217. 



Fig. 217. Panicle. 



(fig. 222), as in the Onion and Cowslip. When the secondary 

 axes themselves divide, and form tertiary axes, which are also 

 arranged in an umbellate manner, a compound umbel is pro- 

 duced. This is seen in the Carrot (fig. 196), the Fennel (fig. 221), 

 and other allied plants, which are hence called umbelliferous, 

 and give the name to the natural order Umbelliferse. In the 

 compound umbel (^g'. 221), the primary umbel a is called the 

 general umbel, and the other umbels, b, b, b, formed by the 

 division of this, partial umbels or umhellules. When the base 

 of the general umbel is surroimded by a whorl of bracts (fig. 

 196, a), they constitute a general involucre ; and if other bracts, 

 b, b, are arranged in a similar manner around the partial umbels, 

 each of these whorls of bracts forms an involucel or partial 



