The Dao Tree is merely a metaphor; anything that can suppress the Cave Heaven counts, whether it is self-condensed or transferred from the Outer World, it's the same.
An Jing planted the 'Heavenly Punishment Divine Wood' with his own 'True Spirit Blood·Ancestor Dragon Seed'. It was his instinct both to perceive the essence of the Great Daoist Principles and thus made the optimal choice, while You Ruhui was lacking, needing to absorb the Scripture of the Great Dao. Only with the profound heritage of the Great Chen Emperor Court could he barely comprehend this layer.
Without You Ruhui's comprehension of this layer, completing the path between the 'Unspeakable Dao' and the 'Speakable Skill' wouldn't perfect the Pocket World Technique.
