菟絲子為常用中藥之一， 來源為旋花科（Convolvulaceae）植物菟絲子Cuscuta chinensis Lam. 的成熟種子。為了解該類藥材之使用情形，於台北及台中地區採逢機取樣方式價購菟絲子檢體50 件，並搜集旋花科之菟絲子、南方菟絲子（Cuscuta australis R. Br.）、大菟絲子（Cuscuta japonica Choisy）、唇形科（Labiatae）之紫蘇子（Perilla frutescens （L.） Britton）及豆科（Leguminosae）之沙苑子（Astragalus complanatus R. Br.）等對照藥材以供比對。市售檢體經性狀特徵、組織切片鏡檢、解離要素及化學法鑑別，並與對照藥材及文獻比對，經確認49 件為菟絲子，1 件為紫蘇子。菟絲子之效用與紫蘇子迥然不同，不宜誤用或混為使用。在本研究蒐集之檢體中並無發現南方菟絲子、大菟絲子及沙苑子誤用為菟絲子之情形。本研究建立菟絲子類藥材之鑑別方法，可供為用藥之參考。

Cuscutae semen, a dried ripe seeds of Cuscuta chinensis Lam. of the Convolvulaceae family, is widely applied to Chinese traditional medicines system. In this study, fifty Cuscutae semen samples were purchased from Chinese herbal stores in Taipei and Taichung areas, Cuscuta chinensis, Cuscuta australis, Cuscuta japonica, Perilla frutescens and Astragalus complanatus were also collected as the authentic materials. Samples were distinguished from the authentic materials by morphology, microscopy and thin layer chromatographic analysis. The results shown that forty-nine samples were identified as Cuscuta australis and one was Perilla frutescens. We also found that some samples were mixed with tiny stones. Therefore, it is important to confirm botanical origin and quality before using herbal medicines.