Piperitone, which accounted for more than 40% of the essential oil of E. dives, may be partially responsible for its antimicrobial activity. The compound has been reported to have antimicrobial activity against Mucora rouxii (Bakkali et al., 2008). Furthermore, it is the main compound (38%) of the essential oil extracted from Mentha pulegium flowers (Mahboubi & Haghi, 2008) which was found to have an inhibitory zone diameter of 21 mm against S. aureus, a result similar to the data for E. dives essential oil recorded in the current study