Biogeographic disjunction

Hello, I’m Amanda McNulty with Clemson Extension and Making It Grow. Biogeographic disjunction is one reason we share so many plants, at least at the generic (or genus) level, with other places. I’m most interested the eastern North American-eastern Asian connection. We have many plants with close genetic material, close enough to share the same generic name – we have red bud, China has red bud. We have tulip poplar, China has tulip poplar, same with sweetgum. As best I can understand, millions of years ago northeastern North America was contiguous, or part of a larger land mass, with southeast Asia. As the large land masses on which these occurred broke apart, the living species were separated and continued to evolve. So, although we have many plants with the same generic names, millions of years of separation lead to different species.