A: Yes, the two are different plants and each oregano has its own "personality," according to Patty Erd, co-owner of The Spice House store chain. She described Mexican oregano as being more robust than Italian or Mediterranean oregano and better suited to full-flavored chile-spiked dishes.
In his book, "Rick Bayless's Mexican Kitchen," the Chicago-based restaurateur, television cooking show host and author wrote that Mexican oregano is "considerably different" than the Mediterranean type. Just take a sniff.
"The Mexican is pungently grassier (think fresh-mown hay) and more floral,'' Bayless wrote. "The Mediterranean more anisey and sweeter (reminiscent of the aromas from a pizza parlor."
Mexican oregano or lippia graveolens is a member of verbena family, according to the website of the Brooklyn Botanic Garden (bbg.org). There are a number of different Mexican oregano varieties. Diana Kennedy, author of "The Cuisines of Mexico," wrote she was told there were more than 13 types
Tom Erd, Patty's husband, noted the oregano you call Italian is found throughout the Mediterranean and might be called Greek or Spanish or Turkish oregano depending on its origin. This oregano, or Origanum vulgare, is interchangeable, he said.
"If you have Greek oregano and the recipe calls for Italian, you're fine,'' Tom Erd noted. "But if you have Mexican oregano and the recipe calls for Italian, you're not …The flavors are quite different."