Terpenoids from Inula sericophylla Franch. and their chemotaxonomic significance

► 23 known terpenoids were isolated from Inula sericophylla Franch. for the first time. ► Structures mainly belonged to thymols, pseudoguaianolides, and xanthanolides. ► Seven isolates were identified to be major constituents of I. sericophylla. ► The crude extracts of five Inula species were compared by HPLC-DAD. ► The genetic relations between I. sericophylla and other Inula species were discussed.