DEFINITE INFLORESCENCE. 



161 



339. When the leaves become very small, and are transformed 

 into true bracts, this whole system forms a single inflorescence, and 

 has received the name of cyme. As 

 the definite inflorescence occurs in a 

 marked degree in the cyme, it has 

 hence been called cymose; and the 

 cyme itself, according to its divisions, 

 has been characterized as dichotomous 

 or trichotomous. In figs. 249 and 

 250, the cyme is represented hi two 

 species of Cerastium, belonging to the 

 natural order Caryophyllaceas, 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. 248; the flowers at a' 

 a' being the termination of the pri- 

 mary axis and expanding first, the 



Fig. 248. Flowering branch of Erythra?a centaurium. \ Primary axis, a" a", Two secon- 

 dary axes, u"' '" a'", Tertiary axes, four in number, a"" a"" <<"", Quaternary axes, eight in 

 number. /, The flower in various stages of development. /', Solitary flower which has passed 

 into fruit, terminating the primary axis. /", Flowers less advanced, terminating the secondary 

 axes. /'". Flowers in bud at the extremity of the tertiary axes, and so on. Inflorescence 

 definite or determinate. Evolution of flowers centrifugal. 



Fig. '249. Inflorescence of Cerastium grandiflorum. b b l>, Opposite bracts produced at each 

 of the branchings; The axes are indicated as in last figure. The primary axis, a', ends in u 

 flower which has passed into fruit. Inflorescence determinate. Evolution of flowers centrifugal. 



Fig. 250. Inflorescence of Cerastium tetrandrum. Letters have the same meaning as in the 

 last two figures. In the quaternary axes, a"", the inflorescence becomes lateral by the non- 

 development of the flower-buds on one side. 



M 



