DEFINITE INFLORESCENCE. 



183 



the base of these axes a pair of opposite leaves is produced, giving 

 rise to tertiary axes, a a" a", ending in single flowers,/'"/'"/'", and 

 so on. The divisions in this case always take place by two, or in a 

 dichotomous {hi-)(a,, in two ways, and riiiveiv, to cut) manner. Had 

 there been a whorl of three leaves in place of two, the division would 

 have been by three, or trichotomous (rg/^^a, in three ways). 



This inflorescence constitutes the Oyme, by which we mean an 

 inflorescence formed by the successive development of unifloral axes 

 from pre-existing axes, limited in extent only by the vigour of the 

 plant; the floral axes being thus evolved in a centrifugal manner. 

 The cyme, elongated according to its development, has been cha- 

 racterised as biparous (bis, twice, and pario, I produce), or uniparous 

 (unus, one). In figs. 270 and 271, the biparous cyme is represented 



Pig. 270. 



Fig. 271. 



in two species of Cerastium, belonging to the nfitural order Caryo- 

 phyUacese, in which cymose inflorescence is of general occurrence. The 

 leaves in the figures are small bracts giving origin to flower-buds in 

 the same way as in fig. 269 ; the flowers at a a' being the termination 

 of the primary axis, and expanding first, the others being subsequently 

 developed in a centrifugal order. In some of the Pink tribe, as 

 Dianthus barbatus, Carthusianorum, etc., in which the peduncles are 



Fig. 270. Inflorescence (tiparons cyme) of Cerastium grandiflorum. bit. Opposite 

 tracts produced at each of the branchings. The axes are indicated as in last figure. The 

 primary axis, a', ends in a flower which has passed into fruit. Inflorescence determinate. 

 Evolution of flowers centrifugal. Fig. 271. Inflorescence (biparous cyme) of Cerastium 

 tetrandrum. Letters have the same meaning as in the last two iigures. , In the quaternary 

 axes, a"", the inflorescence becomes unilateral by the non-development of the flower-buds 

 on one side. . * - - - - 



