## 4 Discussion  
Conventional identification of plants has usually relied on morphology. However, morphological features, such as the shapes of leaves, infloresences, and flowers, are removed during commercial processing. Since accurate identification of herbal medicine based on morphological taxonomic keys is difficult, a DNA barcode system was established for accurate and reliable discrimination of plant species and botanical origins for herbal medicines [14; 15; 25; 31]. Plant DNA barcoding led to remarkable improvements in the identification of the botanical origins of herbal materials and in the quality control of herbal medicines, but it still cannot be applied to many plant taxa because of failed PCR amplification, insufficient sequence variability between species, and incomplete sequence information [1; 16; 19]. To overcome these limits, the comparative analysis of genomic polymorphisms, using methods such as RAPD and AFLP, and the investigation of new DNA barcode regions using plastid genome sequencing have been conducted for a large number of medicinal plant species [15; 24; 32]. SCAR markers and multiplexed SCAR marker assays, developed using sequence information from genomic analyses, as well as from DNA barcodes, have become popular because the assays are simple to perform and have low analytical cost. To identify the botanical \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**No.** & **Voucher No.** & **Product Name** & **Multiplex-SCAR Result** & **Country** \\ \hline  
\hline \hline \end{tabular}
\end{table} 
Table 4: Sample information and monitoring results of the 37 commercial herbal medicines assessed using our multiplexed SCAR assay. origins of herbal medicine based on the DNA barcoding method, many experimental procedures are needed, such as DNA extraction, PCR amplification, gel electrophoresis and rescue, sub-cloning into the pGEM-T Easy vector, _E. coli_ transformation and incubation, plasmid DNA purification and restriction enzyme digestion (or colony PCR), sequencing of inserted amplicons, and sequence comparison or BLAST search. These experimental processes require approximately three or four days of work. However, the SCAR-based method does not require PCR product extraction from the agarose gel, sub-cloning into the vector and transformation, plasmid DNA purification, sequencing, or even sequence analysis. Thus, this method needs only DNA extraction, PCR amplification, gel electrophoresis, and species identification, and can identify the botanical origin of herbal medicines within a few hours. Moreover, the DNA barcoding method involves additional costs for sub-cloning, transformation into the competent cell, and sequencing, which are not necessary in the SCAR method [21]. Judging from our laboratory experience, these additional costs amount to at least $300-$400 USD for the analysis of 10 herbal medicine samples. Therefore, the SCAR method is much more convenient and less expensive for the authentication of herbal medicines and for the identification of the botanical origins of herbal medicines than the DNA barcoding method [22; 24; 26]. In spite of these disadvantages, DNA barcoding is mightily important for plant species identification with high resolution and for obtaining primary sequence information in species-specific marker development. The roots of several _Adenophora_ species and of other related medicinal plant species, including _G. littoralis_, _C. lanccolata_, and _C. pilosula_, have different chemical properties and biological activities [3; 4; 11]. However, the roots of these three species are consistently mislabeled in herbal markets and used for inappropriate clinical purposes in both Korea and China. Therefore, we analyzed the plant species that have been used as authentic herbal medicines and inauthentic adulterants of Adenophorae Radix in Korea and China. Of note, _A. tetraphylla_ was defined as a synonym of _A.