Traditional healing arts are generally based on a single medicinal plant drug or multiple drugs. The formulae used in some Ayurvedic and Siddha drug preparations are taken even from palm – leaf manuscripts. In such circumstances, the medicinal plant used for the preparation of a drug should be authentic and genuine. The evaluation or standardization of a crude drug involves classical microscopic methods. For the better quality control and standardization processes, the present study attempts anatomical authentication of Ayurvedic plant Thumari. Transverse section of leaf shows adaxial palisade cells consists of circular chambers possess single large calcium oxalate druses. The petiole consists of thick and prominently papillate epidermal layer of cells.  In root the xylem fibres are mostly gelatinous type having thin mucilaginous inner secondary walls. The investigations recorded in the present study provided the basis for microscopic authentication of Ayurvedic plant Thumari.