Yi 乙 — Yin Wood

Yi is the second heavenly stem and the yin form of Wood — traditionally described as the vine or the grass. Where Jia is the tree, Yi is the climbing plant: flexible, spreading, and able to grow around obstacles rather than through them. It is the day master's reference stem in a Yi-day chart.

Yi is the second heavenly stem and the yin form of Wood — traditionally described as the vine or the grass. The Jia-Yi contrast is the clearest illustration of how the tradition reads yin and yang of the same element: same element, opposite strategy.

Traditional descriptions use vine and grass imagery — bending, spreading laterally, persisting by going around. It is grouped under Wood (木) in the five-element system.