46 THE EVOLUTION OF PLANTS 



number of them combined together, as in an 

 Arum or a Willow, the whole group or inflo- 

 rescence answering more or less the purpose of a 

 single flower. The question whether the simpler 

 flowers are primitive, or reduced from more per- 

 fect forms, has been much discussed; certainly 

 reduction is in many cases the true explanation 

 of simplicity, and it may be that this holds good 

 generally, as the older botanists taught. How- 

 ever, we will leave this theoretical question for 

 the present; we shall soon see that the fossil rec- 

 ord has something to say on the point. 



The character of the Angiosperms from which 

 their name is taken is the closed ovary. The 

 importance of this character lies chiefly in its 

 effect on the mode of fertilisation. The ovary 

 being closed, the pollen cannot get at the ovules 

 directly, as it mostly does in the Gymnosperms 

 or naked-seeded plants (Conifers, Cycads, etc.). 

 Hence it is necessary for the pistil itself to arrange 

 for the reception of the pollen. This is accom- 

 plished by the formation of the stigma, a downy 

 or sticky surface, to which the pollen adheres 

 when brought by insects, or blown by the wind. 

 To bring the stigma into the best position for 

 catching the pollen, it is often borne aloft on a 

 long stalk the style formed between stigma 

 and ovary. Thus great demands may be made 

 on the powers of growth of the pollen, for each 



