GROUP IV. PHANEROGAMIA : ANGIOSPEKALffl. 



521 



areas which are easily removed (e.g. Cucurbitacece, Fig. 282). 

 These points are definite in number (1, 2, 3, 4, or more), sometimes 

 very numerous (Malvaceae). 



The Gynce.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 form 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 gynaeceum is then 

 said to be apocarpous (Fig. 335^4), 

 e.g. Ranunculus, Pseonia, and 

 Butomus ; if there is only one carpel (Fig. 335 B), the pistil is 

 said to be apocarpous and simple ; if several carpels in one flower 

 cohere and form a single ovary (Fig. 335 C), 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. 335 D). 



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

 one carpel (Fig. 336 A), the margins of which cohere on the side 



FIG. 334. Germinating pollen-grain of 

 Epilobium (highly mag.) bearing a poll en- 

 tube 3 ; e exine ; i intine ; ab c the three 

 spots where the exine is thicker in antici- 

 pation of the formation of the pollen-tube 

 developed in this case at a. 



A 



FIG. 335. A Apocarpous gynseceum of Aconite. B Simple apocarpous gyntcceum of 

 Melilotus. C Tetramerous syncarpous gynseceum of Rhamnus cathartica. D Ovary of 

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

 g style ; n stigma ; b ventral suture. 



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

 runs is the dorsal surface (Fig. 336 A r), and the midrib itself is 

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



