MOEPHOLOGY OF EEPBODUCTIVE OEGANS 203 



placentation may be best explained on the foliar hypothesis ; 

 and that the formation of the free central placenta of the 

 Primulaceae, Santalacese and some other plants, can only be 

 satisfactorily explained by considering the placenta as a pro 

 duction of the axis. 



In the majority of instances, we find one kind of placenta- 

 tion occurring throughout all the plants of a particular natural 

 order. Thus, the Scrophulariaceae, Ericaceae, and Campanu- 

 laceae present us with axile placentation ; the Papaveracese, 

 Violacese, and Cruciferse with parietal ; and the Caryophyllacese, 



FiGj. 440. 



Fig. 441. Fig. 442. 



Fig. 448. 



Fig. 440. Vertical section of the flower of Armerin. Tlie ov.iry is seen to 

 coiitaiu only a single ovnle suspended from a funiculus or 'stalk. The 



ovule is here said to be reclinate. Fig. 441. One of the carpels of the 



Strawberry with a lateral style. Fig. 44:1i. Carpel of Alchemilla with a 



basilar style. The stigma is capitate. Fig. 443. The carpophore, c, of a 



species of Geranium with the rolled-back carpels, car. 



Santalacese, and Primulacese with free central placentation. In 

 some natural orders the placentation is not constant through all 

 the genera. 



2. The Style. — The style usually arises from the geometri- 

 cal summit of the ovary, of which it is a continuation in an 

 upward direction, as in the Primrose (fig. 395) : it is then 

 termed apical. In other cases, the apex of the ovary becomes 

 inflected towards the side or base, from the carpel or carpels of 

 which it is formed being folded like ordinary leaves in reclinate 

 vernation ; the style then becomes lateral as in the Strawberry 

 (fig. 441), or basilar as in Alchemilla (fig. 442). In the two 



