430 



RELATION TO ENVIRONMENT. 



anthesis extends over a period of time, as it favors cross pollina- 

 tion, favors the formation of seed in case conditions should be 



Fig. 452. 

 Heads of fuller's teazel in different stages of flowering. 



unfavorable at one period of anthesis, distributes the drain on 

 the plant for food, etc. 



B. FLOWER CLUSTERS WITH DETERMINATE INFLORESCENCE. 



829. The simplest mode of determinate inflorescence is a 



plant with a solitary terminal flower, as in the hepatica, the tulip, 

 etc. The leaves in these two plants are clustered in the form of a 

 rosette, and the aerial shoot is naked and bears the single flower 

 at its summit. Such a flower-shoot is a scape. As in the case 

 of the indeterminate inflorescence, so here the larger number 

 of flower-shoots are more complex and specialized, resulting in 

 the evolution of flower clusters or masses. Accompanying the 

 association of flowers into clusters there has been a reduction in 

 leaf surface on the flower-shoot so that the flowers predominate 

 in mass and are more conspicuous. Among the recognized 

 modes of determinate inflorescence, the following are the chief 

 ones: 



830. The cyme. In the cyme the terminal flower on the main 

 axis opens first and the remaining flowers are borne on lateral 

 shoots, which arise from the axils of leaves or bracts, below. 



