THE DIFFERENT FLOWERS. 195 



sure that this latter classification is a practicable one, 

 but it is certainly well to place the English forcing va- 

 rieties in a group alone. 



Pollination Ill-shaped fruits. Cucumbers are mo- 

 noecious plants : that is, the sexes are borne in separate 

 flowers on the same plant. Fig. 67 represents the two 

 kinds of flowers on the common field cucumber. P is 

 the pistillate or fruit-bearing flower. The young cucum- 

 ber, or ovary, can be seen below the petals or leaves 

 of the flower. S shows the staminate flower, which per- 

 sists only long enough to supply pollen to fertilize the 

 pistillate flowers. The staminate flowers are more nu- 

 merous than the pistillate, and they begin to appear 



6j. The pollen-bearing and fruit-bearing flower 



earlier ; a sufficient supply of pollen is therefore insured 

 against all exigencies of weather or other untoward cir- 

 cumstances. Out of doors the pollen is carried from 

 the staminate to the pistillate flower by insects, but pol- 

 len-carrying insects are absent from the greenhouse. If 

 the flowers are fertilized in the house, therefore, the pol- 

 len must be carried by hand. It is certain that some 

 plants of English cucumbers will set fruit to perfection 

 without seeds and entirely without the aid of pollen, 

 but other plants (and in our experience they have been 

 greatly in the majority) utterly refuse to do so. I do 

 14 FORC. 



