Plantago lanceolata
Aucubin, as other iridoids, is found in asterids such as "Aucuba japonica" (Garryaceae), "Eucommia ulmoides" (Eucommiaceae), "Plantago asiatica", "Plantago major", "Plantago lanceolata" (Plantaginaceae), "Galium aparine" (Rubiaceae) and others. These plants are used in traditional Chinese and folk medicine.