TI-IE FLOWER OF THE HIGHER SEED-PLANTS 155 



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

 show of how many carpels the pistil is made up (Figs. 99, 

 100). 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. 



184. Locules of the Ovary; Placentas. — Compound 

 ovaries very commonly consist of a number of separate 

 chambers known as locules. 

 Fig. 113, B, shows a three- 

 loculed ovary seen in cross- 

 section. The ovules are 



not borne indiscriminately .- — — , „ 



by any part of the lining of Fig. 113. Principal Types of Placenta, 

 the ovary. In one-loculed ^, parietal placenta ; i?, central placenta; 

 pistils they frequently grow C', free central placenta ; A and B,trans- 



, . . , Terse sections ; C. longitudinal section. 



m a line running along one 



side of the ovary, as in the pea pod (Fig. 146). The ovule- 

 bearing line is called a placenta; in compound pistils there 

 are commonly as many placentas as there are separate 

 carpels joined to make the pistil. Placentas on the wall 

 of the ovary, like those in Fig. 113, A, are called parietal 

 placentas; those which occur as at B, in the same figure, 

 are said to be central; and those which, like the form rep- 

 resented in C of the same figure, consist of a column 

 rising from the bottom of the ovary are called free central 

 placentas. 



185. Superior, Half-Inferior, and Inferior Ovaries 



When, as in the flower of Fig. 98, the receptacle is rounded 

 or club-shaped and the floral organs arise from it in suc- 

 cessive sets, the flower is said to be hypogynous, from two 

 Greek words, here applied to mean under the pistil, and the 

 ovaries are said to be superior (Fig. 114, I). 



