The Supreme Personality of Godhead said: It is said that there is an imperishable banyan tree that has its roots upward and its branches down and whose leaves are the Vedic hymns. One who knows this tree is the knower of the Vedas.
If this world were a tree, then the other world would be the roots - the part of the plant we can't see, but puts the sap into the tree's veins. The other world feeds this tangible world - the world that can feel pain, that can eat and drink, that can fail; the world that goes around in cycles; the world where we die. The other world is what makes this world work. And the way we help the other world continue is by feeding it with our beauty.
This universe is a tree eternally existing, its root aloft, its branches spread below. The pure root of the tree is Brahman, the immortal, in whom the three worlds have their being, whom none can transcend, who is verily the Self.
- Krishna Yajur Veda - Katha Upanishads 6.1. The Upanishads, Breath of the Eternal, 36
Our lord is a tree growing in heaven - his leaves flutter in the pneuma of our minds - his branches reach down to gaia enfolding, nurturing - divine sap flows through his trunk, bridging oceans of time and space - his roots drink the waters of life. - Krael -
http://ascension2000.com/ConvergenceIII/c315.htm Sacred Legends Of The World Tree (illustrated)