16 VEGETABLE ORGANOGRAPHY. 



Thus, when a spiked flower, instead of having the 

 axis elongated, is found to have an oval or globular 

 one, and as the flowers are very close around it, there 

 results an oval or globular spike which has often been 

 called capitulum ; such are the head of flowers of 

 the Plane-tree, Conoca?yus, &c, the female heads of 

 Sparganium, the globular spikes of several Plantains, 

 and some species of Phyteuma, &c. 



When a raceme presents a very short axis, with 

 numerous flowers, and very short pedicels, there may 

 result from this union of circumstances a kind of globu- 

 lar head or capitulum ; this happens in Cephalanthus. 

 Likewise when an umbel has its pedicels very short and 

 its flowers very compact, it may resemble a true capitu- 

 lum ; this happens in several species of CEnanthe. 



Capitula differ principally from one another in the 

 form of the axis : this is sometimes more or less elon- 

 gated, as in the examples mentioned as being derived 

 from the spike, sometimes it is short and more or less 

 expanded, as in those which appear to be derived from 

 the corymbiform raceme, or the umbel ; but all inter- 

 mediate degrees are found in the same families, such as 

 the Dipsacese for example. "When the axis is reduced 

 to a disc, much expanded, the name of Receptacle, 

 Phoranth, or Clinanth, is given to it, and then the 

 inflorescence receives that of Anthodium or Cala- 

 thide ; but although the terms to designate this kind 

 of inflorescence peculiar to the Compositae, and some 

 neighbouring groups, have been multiplied, it would be 

 difficult to establish a definition which would separate 

 those inflorescences from other capitula. The conical 

 receptacle in Anthemis, the oval one in Sphcsranthus, and 

 the oblong one in Rudbeckia, approach the elongated 

 ones of the capitula of Eryngium and Phyteuma, whilst 

 the flat ones of the Artichoke and Thistle would seem 



