GROUP V. ANGIOSPERM^E. 



405 



The Gyna>ceum or Pistil is always the terminal structure of 

 the flower, occupying the apex of the floral axis. It consists of the 

 macrosporophylls or carpels, which, in the Angiosperms fprm the 

 whole or part of the ovaries, that is, closed cavities containing the 

 ovules. If in a flower where there are several carpels, each of 

 them closes by the cohesion of its margins, they form so many 

 ovaries ; the gynseceum is then said to be apocarpous (Fig. 281 .4), 

 e.g. Ranunculus, Pseonia, and Butomus : if there is only one carpel 

 (Fig. 281 J3), the pistil is said to be apocarpous and simple : if 

 several carpels in one flower cohere and form a single ovary (Fig. 281 

 (7), the gynseceum is said to be syncarpous, e.g. Poppy and Lily. 

 Intermediate forms occur in that the carpels may cohere by their 

 lower ends whilst their upper ends remain free (Fig. 281 D). 



The ovary is said to be monomerous when it is formed of only 



FIG. 281. 4 Apocarpous gynseceum of Aconite. B Simple apocarpous gynseceum of 

 Melilotus. C Tetramerous syncarpons gynsecenm of B/iamnm cathartica. D Ovary of 

 Saxifraga, formed of two carpels which diverge towards the top: t tonu ; /ovaries; 

 g style ; n stigma ; b ventral suture. 



one carpel (Figs. 281 B and 282 A), the margins of which cohere 

 on the side opposite to the midrib. The outer side along which the 

 midrib runs is the dorsal surface (Fig. 282 A r), and the midrib itself 

 is the dorsal suture; opposite to it is the line of cohesion, the 

 ventral suture, which runs therefore along the ventral surface. The 

 cavity thus enclosed (loculus) is not usually divided by dissepi- 

 ments, but it is a simple cavity, as in the Vetch ; such an ovary is 

 said to be unilocular. False or spurious dissepiments, formed by 

 growths on the inner surface, occur in some few instances, as in 

 Astragalus. 



When, on the other hand, several carpels cohere to form a syn- 

 carpous ovary, it is polymerous (di- tri- or tetra-merous, etc). The 

 .syncarpous ovary is unilocular (Fig. 282 B) when the individual 



M.B. H H 



