CHAP. II. INFLORESCENCE. 133 



bears a single flower, as in Eryngium, the umbel is said lo be 

 simple {Jig. 80. a) ; but if they divide and bear other umbels, 

 as in Heracleum, the umbel is called compound ; and then 

 the assemblage of umbels is called the universal umbel, 

 while each of the secondary umbels, or the umbellules, is 

 named a partial umbel. The peduncles which support the 

 partial umbels are named radii. Louis Claude Richard con- 

 fined the word umbel to the compound form, and named the 

 simple umbel sertulum {bouquet) ; but this was an unnecessary 

 change. 



Suppose the flowers of a simple umbel to be deprived of 

 their pedicels, and to be seated on a receptacle or enlarged 

 axis, and we have a capitulum or head, named glomus by some, 

 glomerulus by others. If this is flat, and surrounded by an 

 involucre, the compound flow-er, as it is inaccurately called 

 by the school of Linnaeus, of Compositas, is produced ; which 

 is often named by modern botanists anthodium ; it is also called 

 cephalanthium by Richard, calathidium by Mirbel, calatliium 

 by Nees von Evenbeck. The flowers or florets borne by the 

 anthodium in its circumference ai"e usually ligulate, and difter- 

 ent from those produced within the circumference. Those in 

 the former station are called jiorets of the ray ; and those in 

 the \!aXXq.y, jiorets of the disk. 



All the forms of inflorescence which have been as yet men- 

 tioned are to be considered as reductions of the spike or 

 raceme. Those which are now to be described are decom- 

 positions, more or less irregular, of the raceme. 



The fii'st of these is the jxinicle and its varieties. The 

 simple panicle differs from the raceme in bearing branches of 

 flowers where the raceme bears single flow-ers, as in Poa 

 {fig. 8L) ; but it often happens that the rachis itself separates 

 into irregular branches, so that it ceases to exist as an axis, as 

 in some Oncidiums. This is called by Willdenow a deliquescent 

 panicle. Wlien the panicle was very loose and diffiise, the 

 older botanists named it a jidja ; but this is obsolete. If the 

 lower branches of a panicle are shorter than those of the 

 middle, and the panicle itself is very compact, as ill Syringa, 

 it then receives the name of thyrsus. 



Suppose the branches of a deliquescent panicle to become 



K 3 



