Yan Hu Suo

Corydalis yanhusuo (Y.H.Chou & Chun C.Hsu) W.T.Wang ex Z.Y.Su & C.Y.Wu (Papaveraceae) is a small perennial herb 10-30 cm tall endemic to eastern China, with finely divided ternately compound bluish-green leaves and short racemes of pink to purplish-rose tubular spurred flowers in spring. From the base of the stem it forms a small subglobose to flattened-globose yellow tuberous rhizome 1-2.5 cm in diameter. For Yan Hu Suo, the tubers are dug after the aerial parts wither in early summer, boiled briefly until the centers turn yellow, dried, and often dry-fried with vinegar before use. In TCM, Yan Hu Suo is acrid and bitter in flavor and warm in nature, entering the Heart, Liver, Spleen, and Lung channels; it invigorates blood, moves qi, and is one of the strongest analgesic herbs for many pain patterns.