C226 Who was the one who poisoned the poison?

On the fifth day, Zuo Tangzhong finally found a herb that wasn't on the prescription. This herb was a rare herb, if it was another person who found it, they might not know it, but it just so happened that it was Zuo Tangzhong. He was experienced and knowledgeable, so he recognized that this herb was called Earth mold, it had a cold nature, and it could especially cause a woman to have infertility