The essential oil chemical composition of aerial parts of Erigeron trilobus (Decne.) Boiss. growing wild in Oman

Erigeron trilobus (Decne.) Boiss. is a plant native to Africa, the Arabian Peninsula, Afghanistan to China, and North Indochina. It has a fairly complex nomenclatural history, not completely clear at the moment. In fact, it was formerly known as Conyza stricta Willd. Actually, according to some authors, the accepted name is Erigeron trilobus (Decne.) Boiss., whereas some other authors report it as Eschenbachia stricta (Willd.) Raizada. Its aerial parts essential oil (Et), never previously investigated, was characterised by large quantities of diterpenoids (49.24%) with methyl strictate (26.26%) and methyl nidoresedate (12.78%) as main oil constituents. Furthermore, several angular triquinanes, belonging to a quite rare class of sesquiterpenoids, were identified in the oil. No investigation has been carried out into the EOs of any Eschenbachia ssp., whereas a complete review of the essential oils of the accepted Erigeron ssp. is reported, and their chemical compositions have been compared to Et.