The tree is life in a new creation. The tree is the symbol of subconscient vital. The standing image of the universe — The Tree of Life.
Regarding your question about a complementary soul and marriage, the answer is easy to give; the way of the spiritual life lies for you in one direction and marriage lies in quite another and opposite. All talk about a complementary soul is a camouflage with which the mind tries to cover the sentimental, sensational and physical wants of the lower vital nature. It is that vital nature in you which puts the question and would like an answer reconciling its desires and demands with the call of the true soul in you. But it must not expect a sanction for any such incongruous reconciliation from here. The way of the supramental yoga is clear; it lies not through concessions of these things, not, in your case, through satisfaction, under a spiritual cover if possible, of its craving for the comforts and gratifications of a domestic and conjugal life and the enjoyment of the ordinary emotional desires and physical passions, — but through the purification and transformation of the forces which these movements pervert and misuse. Not these human and animal demands, but the divine Ananda which is above and beyond them and which the indulgence of these degraded forms would prevent from descending, is the great thing that the aspiration of the vital being must demand in the sadhak.