ORGANS OF REPRODUCTION. 205 



of nearly equal length, each bearing a flower, and arranged like 

 the ribs of an umbrella, an umbel is formed, as in the Primrose, 

 Cowslip, &c. {fig. 406). When the secondary axes themselves 

 divide, and form tertiary axes, which are also arranged in an 

 umbellate manner, a compound umbel is produced {fig. 407). 

 This is seen in the Carrot {fig. 375), the Fennel {fig. 407), the 



Fig. 407. 



Fig. 407. Compound umbel of Fennel iFceniculum). 



Fool's Parsley, the Hemlock, and other allied plants, which are 

 hence called umbelliferous, and give the name to the natural 

 order Umbel] iferje. In the compound umbel the primary umbel 

 is called the general umbel, and the others formed by the divi- 

 sions of this, partial umbels or umbellules. When the base of 

 the general umbel is surrounded by a whorl of bracts, they con- 

 stitute a general involucre, and if other bracts are arranged in a 

 similar manner around the partial umbels, each forms an in- 

 volucel or partial involucre. These have been alluded to pre- 

 viously when speaking of bracts. 



On comparing the simple umbel with the capitulum, it will 

 be seen that it bears the same relation to it, as tlie raceme 

 does to the spike. The compound umbel again, may be con- 

 sidered to bear tlie 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 j^erceive that the chief diiference 

 between them arises from the shortening or non-development 

 of different axes, and their varying lengths. Thus, the capi- 

 tulum is a spike with a shortened and enlarged axis, the umbel 

 a raceme with a similar axis, and the raceme a stalked spike. 



