Ku Dou Zi

Ku Dou Zi is the seed of Sophora alopecuroides L. (Fabaceae), a perennial herb or subshrub 30–100 cm tall of arid steppe, gravelly slopes, and saline-alkaline soils across northwestern China (Xinjiang, Gansu, Ningxia, Inner Mongolia) and Central Asia. Stems are erect, branched, and finely silvery-pubescent. Leaves are odd-pinnate with 15–25 elliptic-oblong leaflets each 1.5–3 cm long. Terminal racemes bear dense, pale yellow to cream pea-like flowers in early summer. The legume is moniliform (constricted between seeds), 5–9 cm long, indehiscent, containing 3–7 oval, smooth, yellow-brown to dark brown seeds 5–7 mm long. Seeds contain quinolizidine alkaloids (matrine, oxymatrine, sophoridine, aloperine) and are TOXIC; small medicinal doses are used in TCM to clear heat-toxin, dry damp, and treat dysentery and parasitic infections. Overdose causes neuromuscular and cardiac toxicity; use only under qualified supervision.