Why do flowers naturally reproduce with their own species?

Question

I have always wondered why flowers reproduce with the same species naturally. Why can't the pollen grains get to a different species flower through via the wind, water, or insects?

Answer 1

The issue here is generally genetic compatibility and why closely related species my hybridize while others will not, just like in animals. A wolf and dog may breed and hybridize, just as a nectarine may hybridize with a peach. But even with laboratory interference, we cannot breed a mouse and a wolf for the same reason Oak pollen will not pollinate a geranium if it comes in contact. Most often the exclusionary processes are fundamental genetic mkeup, such as total numbers of chromosomes or different ploidy.