To be male or to be female,that is a question (part three)

Hello everyone,after the last two week's introduction of the gender change in animal,this week we will go to explore another kind of gender changing in plant,which is called dichogamy(雌雄異熟).As you saw the Chinese of dichogamy,you may think it is not as peculiar as last things we introduced.To change this boring image,I'd like to show a extraordinary video to you.Please watch the vedio to the last second.

Magnolia flower

https://www.youtube.com/watch?v=Ja3GJyJ98uI

It's so cool.isn't it?

However,it is not over.If you have the potential of being scientist,you may want to ask“Why？Why do they have this behavior? ”Well,it is apparent that the cause is different from animals'.At first,botanists thought that it is because plants have to reduce the probability of inbreeding(Because self-pollination contribute to inbreeding).Nevertheless,botanists found that self-incompatibility plants,which make themselves inbreed by different time of pollen germination(花粉萌芽), pollen tube growth(花粉管生長), ovule fertilization(胚珠發育), and embryo development(子房形成),also have this behavior.Consequently,it means the reduction of inbreeding is not the purpose that plants have dichogamy. 
Now,botanists think this behavior is to avoid the interference of stamen(雄蕊) and stigma(雌蕊),which prohibit the pollinators to spread pollen due to their volume.The answer may seems a little bit simple,but it does play an important role in causing this phenomena.
All right,these are the whole introduction of the gender of change.Hope all of you enjoy this topic.