SIMPLE AND COMPOUND PISTILS 



129 



The union generally forms the ovary, although this is sometimes 

 developed in large part as a cup-like or tubular growth from the 

 stem under the carpels. Sometimes the union is so complete 



FIG. 134. Flower of stonecrop 

 A, entire flower; Z>, vertical section. After Decaisne 



that the compound pistil has only one style and one stigma ; but 

 frequently the styles remain separate, or the styles may be 

 united and the stigmas separate, or at least lobed so as to show 

 of how many carpels the pistil is made up (Figs. 123, 124). 

 Even when there is no external sign to indicate the' compound 

 nature of the pistil, it can usually be recognized from a study of 

 a cross section of the ovary. 



156. Locules of the ovary; placentas. Compound ovaries 

 very commonly consist of a number of separate chambers known 

 as locules. 1 Fig. 135, B, shows 

 a three-loculed ovary seen in 

 cross section. The ovules are 

 not borne indiscriminately by 

 any part of the lining of the 

 ovary. In one-loculed pistils 

 they frequently grow in a line 

 running along one side of the 

 ovary, as in the pea pod (Fig. 

 343). The ovule-bearing line is 



C 



FIG. 135. Principal types of placenta 



A, parietal placenta ; B, central placenta ; 

 C, free central placenta ; A and B, trans- 

 verse sections; C, longitudinal section. 

 After Strasburger 



called a placenta ; in compound pistils there are commonly as 

 many placentas as there are separate carpels joined to make the 



Often (less correctly) called cells. 



