Qt> PISTIL. [CHAP. 



of adjacent carpels. And so we often find, that when 

 syncarpous pistils are ripe their carpels separate from 

 each other, each dissepiment splitting into two plates. 



21. From the circumstance that the ovules develope upon 

 the margins of carpels, it must follow that when two or 

 more carpels cohere, and their margins are infolded so as 

 to meet in the centre of the pistil, the ovules must also 

 be attached in the centre or axis. Their attachment, or 

 placefitation^ as it is termed, is then termed axile. You 

 find this well shown in Lily or Crinum, where there are 

 three carpels ; Solanum, where there are two ; and Orange, 

 where there are many, cohering. 



But in many syncarpous pistils, although the carpels 

 cohere, their margins are not infolded to such a degree 

 as to reach the centre and become united there into an 

 ovule-bearing axis. When such is the case, the placentation 

 is described z.^ parietal. We find all grades 

 of development of these dissepiments, from 

 the Violet and its allies, with parietal placen- 

 tation (the carpels not being infolded at all, 

 and the ovules arranged in lines upon the 

 Fig. 74. Transverse j^sidc of the one-cellcd ovary), to the Lily, 



section of a one- .'/' y' 



thUre"^ arfe'tai '' iJ ^"^ which thc carpellary margins are inflected 

 centas and indefi- j-q the ccntrc, and the placentation is con- 



nite ovules. , •»• 



sequently axile. The pistil of Poppy is 

 intermediate ; the margins of the numerous united carpels 

 which compose it projecting into the cavity of the ovary 

 without quite reaching to the centre. The placentation of 

 this plant is exceptional, the ovules being spread over the 

 sides of the partial dissepiments, instead of being confined 

 to their inner edges. 



In Pinks and Stitchworts the placentation is axile, but 

 the dissepiments are lost before the ovary is fully grown, 



