Abstract:We investigated the structural development of roots with their dynamic accumulation of saponins in Polygala tenuifolia by anatomical, histochemical and phytochemical approaches. The saponins were distributed in the root parenchyma, and the secondary phloem was the main storage region of saponins. We took senegenin as an evaluation index to analyze the regularity of saponins accumulation. During the growth period from April to October, the percentage of senegenin content of roots in different years had dynamic variant trend, the senegenin percent content had the similar result, and the order was annual roots>biennial roots>triennial roots>quadrennial roots showing that the younger root had higher content. The length, diameter, thickness of the “skin areas” and dry weight as well as the total senegenin content of roots increased most quickly from the second to the third growth year. Considering the yield and the quality, the middle ten days of August in the third growing year was optimal collecting period for the drug of P.tenuifolia.