Island Plant Life

The islands are surrounded with water. Besides this, there is vegetation on each of these islands. 
According to scientists, there are three ways plant life began on islands. 
The first way is that there was vegetation on the islands before they were cut from a bigger parts of land. 
The second way, is that the wind blows the seeds.  The seeds fly in the air for long distances. 
The last way, is that birds carry the seeds from place to place.