Sophora flavescens

Sophora flavescens, known in Chinese medicine as ku shen (苦参), is a deciduous subshrub in the family Fabaceae, native to China, Korea, Japan, eastern Russia and parts of South and Southeast Asia, where it grows on sunny hillsides, grassy slopes, roadsides and the margins of fields. It reaches about 1 to 1.5 metres in height, with green, ridged stems arising from a stout, woody, pale yellow root that is intensely bitter. The leaves are pinnately compound with numerous lanceolate to elliptic leaflets. The pale yellow to whitish pea-like flowers are borne in long terminal racemes in summer, followed by elongated, slightly constricted pods that are somewhat beaded between the seeds. The thick root (Radix Sophorae Flavescentis) is the part used medicinally and is rich in quinolizidine alkaloids such as matrine and oxymatrine. The plant is widespread and weedy in disturbed open habitats across its native range.