VARIATIONS IN STRUCTURE 



291 



ovary, usually indicates the number of carpels which com- 

 pose it. (See Figure 114.) Some ovaries of compound 

 pistils have but one seed compartment. In such cases the 

 number of carpels is usually indicated by the number of 

 rows of ovules along the 

 walls of the ovary. The 

 walls of the ovary are usu- 

 ally raised in Httle ridges to 

 which the ovules are at- 

 tached. These ridges are 

 called placenta (singular, 

 placenta). 



The most striking varia- 

 tion of the gynoecium is the 

 variation in the position of 

 the ovary with reference to 

 the rest of the flower. 

 (Study Figure 115.) You observe that ovaries have three 

 distinct positions with reference to the rest of the flower. 



Fig. 114. — Three types of pistils. The 

 figure farthest at the left shows three 

 simple pistils composed of separate 

 carpels. The other figures show com- 

 pound pistils composed of united car- 

 pels. 



Fig. 115. — Diagrams illustrating hypogyny, perigyny, and epigyny. See context. 



In the first of these the other parts of the flower are all 

 attached to the receptacle beneath the ovary. This ar- 

 rangement is called hypogyny. (The word signifies under 

 the gyncecium.) In the second arrangement the'other parts 



