You are touching upon some powerful symbolism here: http://opsopaus.com/OM/BA/Gallery/InvertedTree.html
but more so to the point is Breck Outland with his "The Inverted Tree: an Urthonic Crisis" - I still need to fix his VAG page (all Flash content is invisible - maybe I should do that right now), but his drawing and the text are there: https://www.vagallery.com/breck-outland.html
PS: There is a inverted tree sculpture on the Donauinsel in Vienna.