Boab trees are of the genus Adansonia. In Africa and Madagascar these trees are known as baobab. The Australian species Adansonia gregorii (named in honour of explorer Augustus Gregory) has been evolving for 190 million years. They are thought to have originated from plants washed ashore from Madagascar, although this is not universally accepted.
It is sometimes claimed that the boab is the oldest living thing in Australia. But – stromatolites!