This was an interesting podcast, by Dr Michael S. Heiser. He explains Ezekiel 31 and the cosmic tree motiff.
Simply put (though his primary focus is how it links to the divine council), Ezekiel 31 describes a huge cosmic tree with it’s roots in the subterranean sea upon which the earth rests and it’s top in the clouds, thus binding the universe together (those who know their Norse Mythology will know what I mean).
I find this is yet another reason why we should not expect the Bible to be scientifically accurate.
Ezekiel is being told to give a vision he receives to Pharaoh as it describes the coming destruction of Egypt at the hands of Babylon.
2 “Son of man, say to Pharaoh king of Egypt and to his hordes:
The trees described are nations (e.g. Egypt and Assyria) and the great tree described is Egypt. This has nothing to do with the universe as far as I can tell. Even for a vision, the language is fairly plain in my opinion.
This interpretation of the trees being nations of the world is also consistent with the Book of Daniel.
The tree is clearly not Egypt or Assyria but rather a tree which is compared to both. As Mike explains, there are strong parallels with this tree and the cosmic Mesu tree in mesopotamia.