Botanical characterization to authenticate sophorae tonkinensis radix et rhizoma based on anatomy and molecular analysis

Sophora tonkinensis Gapnep. (Leguminosae) is distributed in Vietnam and southwest China, and its roots and rhizomes have been used to reduce a fever, to treat inflammation, or to relieve pains as a traditional medicine in East Asia. It was once reported that the original plant of this traditional medicine was S. subprostrata Chun & T.C. Chen, which is currently treated as the same species with S. tonkinensis. Even though roots and rhizomes of S. tonkinensis are commonly used as 'Shandougen', which is the local name for the herbal medicine, those of different plants are frequently sold in the markets with the same name. We carried out anatomical examination as well as molecular analysis to set up the criteria to authenticate roots and rhizomes of S. tonkinensis. In the root, vascular cambium is well developed with cortex, phloem, and xylem. In xylem, vessel elements are roundish polygonal in shape and alternated with xylem fibers in cluster. Xylem parenchyma rows in 2–3 cells in parallel with rays. Parenchyma cells contain starch grains, which are also found in ones of cortex. Periderm, over 20 cell thick, is easily taken apart. In parenchyma, oil cells are often observed. Sequence analysis of psbA-trnH Intergenic Spacer region of cpDNA could discriminate varieties recognized in S. tonkinensis.