22 



STRUCTURAL BOTANY 



in the open flower. Each of these four leaves is called 

 a sepal, and collectively they form the calyx ; as the 

 sepals are not joined together, the calyx is said to be 

 polysepalous. 



A 



FIG. 12. Transverse section through a flower-lud. A t posi- 

 tion of axis of inflorescence ; S, sepals (four in number) ; 

 p, petals (shaded) (four in number) ; st, stamens (six 

 in number, each with four pollen-sacs) ; 0, ovary (of two 

 carpels). Compare the diagram, Fig. 13. Magnified 

 about 12 times. (R. S.) 



The diagram, Fig. 1 3, represents as it were the ground 

 plan of a flower, and shows the relative position of all 

 its parts. In order to fix this, it is necessary to know 

 how the flower is placed with reference to the axis of 

 the inflorescence. This axis is indicated by a dot in 

 the diagram. It will be seen that the two outer 



