58 



PLANTS 



125. The gynoeciiim is the organ or set of organs formed by 

 the fourth or inner circle of floral leaves. The individual 

 leaves (carpels) composing it may be more or less united to 

 form a single structure or, not infrequently, the number of 

 carpels may be reduced to one, which then occupies the centre 

 of the flower. In case there is only one carpel, or if the carpels 



are separate, each one constitutes a simple 

 pistil, which must be regarded as having 

 been formed by the rolling of the blade of 

 the carpellate leaf, so that its opposite 

 edges meet and unite and thus enclose 

 a flask-shaped cavity. The pistil thus 

 formed may be described as consisting 

 of the ovary — the cavity of the flask with 

 its enclosing walls, the style — the neck of 

 the flask — and the stigma, a slight glandu- 

 lar enlargement at the top of the style. 

 (See Fig. 27.) 



126. Within the cavity of the ovary 

 and attached to its walls are one or more 

 minute bodies, the ovules, which are 

 destined to develop into the seed. The 

 specialized part of the ovary wall to which 

 the ovules are attached is the placenta. 

 (See Fig. 27.) 



127. Pistils are frequently compound, i. e., made up of more 

 than one carpel. In such cases there may be various degrees 

 of fusion of the component leaves, ranging on the one hand from 

 a slight external union of the ovary walls to such complete 

 fusion on the other, that the only evidence of its compound 

 nature is to be found in the number of placentae. The number 

 of pistils in one flower varies from one to many. 



128. Both androecium and gynoecium are essential^and with- 

 out either one the flower is incapable of performing its function. 



Fig. 28. — One of the 

 four leaf-like carpels of 

 the Chinese parasol tree 

 (Sterculia) with several 

 seeds attached to its 

 margins. The carpels 

 separate early and as- 

 sume a leaf-like form. 



