CHAPTER II 



THEIR RELATION TO PLANTS AS BENEFACTORS 



WHILE, in a general way, insects frequent plants 

 merely to feed on them, yet this feeding is not neces- 

 sarily destructive and may even contain an element of 

 advantage. Hence we find that, far from developing 

 structures to repel, many plants produce attractive 

 flowers and secrete nectar as an invitation to insects to 

 call upon or visit them. 



Flowering plants as a rule have two kinds of sexual 

 organs: the pistil connected with the seed or female 

 element, and the stamens, producing the pollen or male 

 element. Fertilization takes place when the pollen or 

 male element is brought into contact with the receptive 

 surface of the pistil, and this pollination may be produced 

 in many different ways. Sometimes the same flower 

 has both pistil and stamens, and the pollen from the 

 latter may be discharged so as to come into immediate 

 or direct contact with the former. But this is not 

 always the case, for the pistil may not reach the recep- 

 tive condition until after all the pollen has been removed 

 from the stamens and, on the other hand, the pistil 

 may become receptive before the pollen on the same 

 flower is mature. In such cases there must be polli- 

 nation by some outside agency. Many flowers are of 

 one sex only, i.e., either pistillate, bearing female 

 organs only, or staminate, bearing male organs only: 

 and sometimes an entire tree or plant may bear flowers 

 of one sex only. Here again pollination by some carrier 

 is necessary and among the carriers the most active 

 agents are the wind and insects. 



