In Wu Ling San, which herb is the chief herb?

• A. Fu Ling
• B. Ze Xie
• C. Zhu Ling
• D. Bai Zhu

Answer: (B)

The main idea is that the chief herb is the one most directly driving the formula’s main action: draining dampness and moving water out of the body. In Wu Ling San, that primary driver is Ze Xie, the Alisma rhizome, because its strongest function is to drain dampness from the lower burner and promote urination. This targets the core pattern of water retention with dampness, directly reducing dampness and aiding downward water flow.

The other herbs support this primary action. Fu Ling helps transform dampness and tonify the spleen, Bai Zhu strengthens the spleen to prevent improper water movement, and Zhu Ling also promotes urination to assist drainage. Gui Zhi aids in dispersing exterior patterns and helps harmonize the formula, ensuring the water-dampness movement remains balanced. But Ze Xie provides the principal mechanism for clearing dampness and moving water, which is why it’s considered the chief herb.