## 1 Introduction  
According to the Korean Herbal Pharmacopoeia [1, 2], Lepidii seu Descurainiae Semen refers to the dried ripe seeds of _Descurainia sophia_ ([PERSON] or _Lepidium apetalum_ [PERSON], which belongs to the family Brassicaceae (Cruciferae). Lepidii seu Descurainiae Semen is used in Northeast Asian countries, including Korea, China, and Taiwan, as an herbal medicine, called \"Jeong-Ryeok-Ja\" in Korean and \"Ting-Li-Zi\" in Chinese. Although the Pharmacopoeia of the People's Republic of China and the Taiwan Herbal Pharmacopoeia have designated the seeds of _De. sophia_ or _L. apetalum_ as Descurainiae Semen (southern lepidium) or Lepidii Semen (northern lepidium), respectively, seeds of both plant species are sources of the same herbal medicine [1, 2, 3, 4, 5]. In Korea, prior to the revision of the Korean Herbal Pharmacopoeia (KHP) in 2013, the herbal medicine Jeong-Ryeok-Ja was believed to be derived from the seeds of _Draba nervosa_ L. and _L. apetalum_ as Semen Drabae et Lepidii [2, 6]. Seeds of _Dr. memorosa_ and _L. apetalum_ are currently designated as sources of the same herbal medicine in the Pharmacopoeia of Democratic People's Republic of Korea [1, 7]. Traditionally, Lepidii seu Descurainiae Semen has been used as a demulcent, laxative, and an apereient drug [8]. Studies have shown that this herbal medicine has anti-inflammatory, analgesic, antipyretic, anticancer, and antioxidant properties. It is also used to treat functional constipation [9; 10; 11; 12]. However, a number of misuse issues have emerged due to the inaccurate identification of seeds of other plant species as Lepidii seu Descurainiae Semen [2; 13; 14]. For example, seeds of _Dr. memorosa_, defined in the unrevised KHP before 2013, are currently sold in herbal markets as Lepidii seu Descurainiae Semen. Similarly, seeds of _Erysimum cheiranthoides_ L. and _Erysimum macilentum_ Bunge (family Brassicaceae) are often found as adulterants in Lepidii seu Descurainiae Semen because of the morphological similarities among these species. The plant species _L. apetalum_ is strictly distributed in the northern part of the Korean peninsula; however, _Lepidium virginum_ L., a close relative of _L. apetalum_, is found in all provinces of Korea. Therefore, it is likely to replace _L. apetalum_. The National Institute of Food and Drug Safety Evaluation has alerted consumers to discriminate between authentic and inauthentic Lepidii seu Descurainiae Semen [15]. Morphological analysis [2] and molecular studies [16] have been conducted to facilitate the accurate identification and authentication of original plant species with morphological similar species. However, the identification of minute seed medicines based on morphological characteristics has not been investigated. It is important to accurately identify minute seed medicines. However, the seeds are difficult to distinguish by the naked eye. Therefore, studies using stereomicroscopes have been conducted to facilitate morphological identification of these seeds [17; 18]. A macroscopic authentication study of Chinese materia medica seeds and fruits in the United Kingdom (U.K.) market was carried out to guide quality control of herbal medicine [19]. Production of mucilage by distinguished epidermal cells during hydration (myxocarpy) has been observed by light microscopy [20]. The presence or absence of a mucilage reaction is a useful diagnostic characteristic for the taxonomic identification of plant species [20; 21; 22; 23; 24; 25; 26; 27]. Investigation of the micromorphological characteristics of seeds using a scanning electron microscope has been used to identify and distinguish species [28; 29; 30; 31; 32; 33; 34]. Thus, these techniques can be used to authenticate and distinguish genuine species from close relatives, inferior substitutes, adulterants, and counterfeits.