This is a picture I took in Mexico of an Oregano plant, also known as Wild Marjoram, but should not be confused with Origanum majorana, which is Marjoram. There are many common names of one plant that are confusing, so it’s best to use the universal Latin name to identify a plant. Latin names are usually in italics, to differentiate in print. The first Latin name is called the Genus, and the second name is the species of the plant. While marjoram and oregano are from the same Genus Origanum, they are very different species: Origanum vulgare is Oregano, and Origanum majorana is Marjoram.
The leaves on the Mexican Oregano are scalloped, unlike the smoother edged varieties in my garden.
What other differences are there between Mexico Oregano and Greek Oregano?
For starters the Mexican Oregano is grown in Mexico, and the Greek Oregano is grown in Greece.
Plants that have the same Latin name can have different chemical constituents depending on where they are growing. Habitat influences plants, and alters chemistry because of factors like altitude, soil, climate, rainfall, and a host of other conditions.
These types of plants are referred to as Chemotypes. They are the same plant in Latin name, but due to habitat may have different plant chemistry.
Different breeding and natural selection of a Genus like Thymus, Thyme, creates many varieties of species and subspecies.
The Mexican Oregano may have the same name as the Greek Oregano growing in my garden, but it looks different and tastes different. They may have mainly the same chemical constituents that make up Oregano, but there is enough variation in plant chemical constituents to change flavours and aroma. They may be used interchangeably, but expect different results.