FLOWERS AND FRUITS 143 



Uses of the Parts of a Flower. 



Plants, such as the cucumber, in which the stamens 

 and pistils are in separate flowers, are very convenient to 

 employ in endeavouring to understand the uses of the 

 various parts. Keeping a cucumber plant under obser- 

 vation, we find that cucumbers are never borne on the 

 staminate flowers, but always on the pistillate flowers. 

 Of what use, then, are the staminate flowers ? 



Experiments have often been made (and any one 

 with care can repeat them), which clearly show that both 

 staminate and pistillate flowers play a part in the pro- 

 duction of seeds and fruit. A pistillate flower, tied up 

 just before it opens, in a thin paper bag, and kept tied up, 

 forms no fruit, but its ovary shrivels up and withers like 

 the rest of the flower. A second pistillate flower, also tied 

 up before it has opened, but which when open has had 

 some pollen from a staminate flower put on its stigma, 

 forms fruit. The petals of this flower wither up like the 

 first, but its ovary does not, but commences to grow and 

 finally forms a ripe fruit with seeds in it. 



Thus we learn that for the production of fruit and 

 seeds, it is necessary for the stigma of the flower to have 

 some pollen of the same kind of plant placed upon it 

 When this has been done the flower is said to ^pollinated. 

 The actual events which take place as the results of pol- 

 lination cannot be studied without more apparatus than 

 is at our disposal. They will be found fully described 

 and illustrated in most botanical text-books. The final 

 result of pollination is the fertilisation of the flower, and 

 only when this has happened are seeds formed. Pollina- 



