292. Ill regard to tlit- evolution of the inflorescence, that is, 

 the mode of succession in the development of the flowers, bota- 

 nists have recently obsen^cd two important distinctions, namely, 

 the centripetal .m\d the centrifugal, the former resuitiuf'" from 

 axilhuy, and the other from terminal flowers. N 



293. In CENTRIPETAL infloresccnce the evolktion (blossomins') 

 of the flowers commences with those of the circumference (or 

 the base) and proceeds towards the centre (or the summit), as 

 in the Umbelliferaj and the Crucifero?. 



a. Tlie student vail readily perceive that the circumference of a depressed (flat- 

 toned, inflorescence corresponds to the base of a lengthened one; and also that the 

 centre of the former answers to the summit of the latter. For when the axis, or 

 rachis, is lengthened, it is the centre vdiich it bears along with it at its apex, leav- 

 ing the circumferanec at the base. 



294. In CENTRIFUGAL infiorcsceuce the blossoming com- 

 mences with the terminal and central flc»wcr, and proceeds 

 towards the lateral flowers, or those of the ciicumference. Ex, 

 Hydrangea, elder, and the pink tribe.' 



a. ' This mode of inflorescence is generally indicated by the presence of a soli- 

 tary flower seated in the axils of the dicliotomous (forked) branches.' All tlic 

 flowers are considered terminal, because they do m fact (except the fu'st whieli 

 terminates the axis) tenninate lateral branches saccessi^y produced at the node 

 ne.\.t below the primary flower. ' This is bcf.r.dfaily ill^tated iu Spergula. 



FIG. 37. — iSIodes of inlorescenee ; 1, centrifugal inflorescence (cymL) of Cerastiiim maxi 

 mum ; 2, fascicle ; 3, centripetal inflorescence (cor>'mb) ; 4. spike. 



295. Sometimes we And these tvi'o modtf. of inflorescence 

 combined in the same plant. In the Compositie, as \Di. Gray 

 remarks, the heads, which may be called the 2^artial inflorcs- 



