\ I 



90 ELEMENTS OF STRUCTURAL BOTANY. 



if the stamens are hidden in the tube of a gam'^petalous 

 corolla, they are said to be included, but if they protrude 

 beyond the tube they are exscrted (Fig. IJJO). 



137. The Pistil. This is the name given to the 

 central organ of the flower. It is sometimes also called 

 the cjyncecium. As in the case of the stamens, the 

 structure of the pistil must be regarded as a modifica- 

 tion of the structure of leaves generally. The pistil 

 may be formed by the folding of a single carpellary 

 leaf as in the Bean (Fig. 159), in which case it is 

 simple ; or it may consist of a number of carpels, either 

 entirely separate from each other, or united together in 

 various ways, in which case it is compound. If the car- 

 pels are entirely distinct, as in Buttercup, the .pistil 

 is apocarpous ; if they are united in any degree, it ic 

 syucarpous. 



138. In our examination of the Marsh Marigold (Figs. 

 24, 25) we found an apocarpous pistil of several cari)els. 

 "We found also that each carpel contained a number of 

 seeds, and that, in every case, the seeds were attached to 

 that edge of the carpel which ivas turned toivarcls the centre 

 of tliefloiver, and that, as the carjiels ripened, they 

 invariably split open along that edge, but not along the 

 other, so that the carpel when opened out presented 

 the appearance of a leaf with seeds attached to the 

 margins. The inner edge of a simple carjiel, to which 

 tliQ ^eds are thus attached, is called the ventral suture, 

 the opposite edge, corresi^onding to the mid-rib of a 

 leaf, being the dorsal suture. 



13^. If we suppose a number of simple carpels to 

 opproa^jlf^ch other, and unite in the centre of a flower, 

 evident that the pistil so formed would contain as 

 mar.v cells as there were carpels, the cells being separ- 



