CH. xin FLOWER AND INFLORESCENCES 165 



performs a special work in connection with the reproduction 

 of plants. 



4. The Gyncecium, or pistil, is built up of carpels. The 

 pistil constitutes the female organ of reproduction and always 

 occupies the centre of the flower. It produces ovules, which 

 under healthy conditions form the future seeds. The following 

 experiments will make clear what is meant by floral leaves. 



EXPT. 156. Examine a Wallflower. Note 



(i) The calyx on the outside of the flower. In this case it is built up 

 of four sepals, each of which is long and hairy. The two inner sepals 

 are swollen at the base. Each sepal, which is either yellowish or 

 brownish-red in colour, can be pulled off without tearing it from its 

 fellows. 



(ii) Standing just within the calyx, and alternating with the sepals, 

 four yellow or reddish-brown leaves will be found. These form the 

 corolla. The petals are arranged in the form of a cross and are the 

 largest leaves of the flower. 



(iii) Within the corolla six stamens occur. Four are long and two 

 short. Remove one : it consists of (a) a stalk, called a filament ; (b) a 

 head the anther. Open the anther : it contains a number of micro- 

 scopic pollen grains. 



(iv) The centre of the flower is occupied by two carpels joined to- 

 gether, which form the pistil, and is divided at the apex into two lobes. 

 The long somewhat swollen body forming the lower part of the pistil 

 is called the ovary. The lobes at the apex of the ovary form the 

 styles^ and the tips of these form the stigmas. 



(v) Open the ovary : a number of rounded bodies are seen the 

 ovules. 



EXPT. 157. Examine the flower of a Buttercup. Note 



(i) The five sepals (green and leaf-like in appearance) on the outside 

 forming the calyx. 



(ii) Five yellow petals, constituting the corolla, are found just within 

 the calyx, filling the gaps between the sepals. 



(iii) A number of yellow stamens, each consisting of a filament and an 

 anther. The anthers, if ripe, are full of pollen. 



(iv) Many small green carpels not united together as in the wall- 

 flower make up the pistiL Each carpel possesses at its base a swollen 

 portion the ovary and above this the style and stigma can be dis- 

 tinguished. 



(v) In each ovary a small egg-shaped ovule is to be found. 



Flower. The following reasons lead us to believe that a 

 flower is a modified shoot. 



i. The flowers are produced either at the apex of a shoot or 

 in the axil of foliage leaves. This is just the position in which 

 we find branches or shoots (p. 16). 



