44 THE STORY OF PLANT LIFE 



types of insects adapted to each, and their order of 

 development or evolution. 



The order in which each flower upon an inflores- 

 cence opens is another subject which demands a series 

 of observations. In some cases the first flower to 

 open is at the top, in others the lower flowers open 

 first. 



The occurrence of double flowers may be due to 

 various causes. Frequently the stamens become 

 petals. In others the petals become stamens. It is 

 considered that the latter gave rise to the former. 



The stamens exhibit a great deal of variety in 

 number, form, and structure. They are generally in 

 a ring around the centre of the flower, and lie in such 

 a relation to the usually central stigma that pollen is 

 brought to the stigma of the same flower, or can 

 be transferred to that of another flower, either on 

 the same plant, or on a different one by different 

 agencies. 



The stamens are not usually conspicuous. They 

 are pollen-bearing, and in them we come a stage 

 nearer to pollination preceding fertilisation, the 

 latter the last function in the life cycle of the plant, 

 before a fresh individual is dispersed and in due 

 course enabled to germinate. 



Interesting observations as regards the stamens 

 may be made as to the time of opening, i, e. either 

 before, at the same time as, or after, the stigma 

 is ripe. Another feature is the way in which the 

 anthers ripen. They may open towards or away 



