Quality regionalization study on Gentianae Macrophyllae Radix Analysis of commercial specifications and grades of wild and cultivated Gentianae Macrophyllae Radix based on multi-indicative constituents Studies on quality variance and genetic diversity of Gentianae Macrophyllae Radix from different habitats in Shaanxi Province Simultaneous determination of five iridoids in Gentianae Macrophyllae Radix and their local variety by HPLC