They look different, they smell different, they taste different they even grow differently, so why does oregano and marjoram often get thought of as one and the same? Well we’ve got the science community to thank for that by giving them the same genera name origanum. Marjoram is Origanum marjorana (it used to be Marjorana hortensis). Oregano is Origanum vulgare. They are part of the mint family (Lamiaceae).
Origanum is derived from two Greek words, oros (mountain) and ganos (joy), meaning they looked real pretty growing on the hillsides!
Marjoram looked pretty on the hillsides of Portugal where it is a native and Oregano looked pretty on the hillsides over Asia, Europe and North Africa.
Also to confuse matters Oregano has been and can be, called Wild Marjoram whereas Marjorams full (common) name is Sweet or Knotted Marjoram. Then there is also Pot Marjoram Origanum onites a species found in Sicily, Greece and Turkey. Now lets twist the confusion a little more with Winter Marjoram Origanum heracleoticum which is now known as Origanum vulgaris hirtum commonly known as Greek Oregano and thought of as the one to have for flavour. I could go on, there are quite a few species mostly ornamental but still interesting, I have a compact marjoram that I was given a cutting of last year from a customer. It’s cute but it’s flavour is pretty mild.

Compact Marjoram
Soo, how do you know which one you’ve got and/or how do you identify that you’re buying the right plant for your purposes (I’ve seen plants mislabeled, tut tut).
Oregano Origanum vulgare

Origanum vulgare
If you want to have medicinal benefits with your plant this is the one that you want. Origanum vulgare can be used for coughs, fevers and tension headaches. The antiseptic properties (thymol and carvacrol) make oregano useful for inflammations of the mouth and throat and used externally for infected cuts and wounds. The aerial parts of the herb is gathered and dried as soon as it flowers and here is where we can identify O. vulgare from the others as its flowers are a pink colour. The leaves are a dark green colour, roundish with pointed ends and it grows with a creeping habit, in the ideal spot (good sun and good drainage) it can get a bit OTT! But it’s easy to curb it as it creeps along; unlike mint that dives down and comes up wherever it can. If you can’t find Greek oregano this one is fine as a culinary herb. Some contest it but I personally have found that it has a good strong flavour if grown in a well sunny dry position.
Marjoram origanum marjorana

Origanum marjoram
Sweet marjoram grows upright with reddish stems, the leaves aren’t as hairy as oregano vulgare and during the flowers come out of little knotted balls~ hence its other name Knotted marjoram. It looks quite cool. The taste is entirely different to oregano, oregano is described as balsamic thyme whereas marjoram is a sort of sweet salty lemony minty flavour (that description is with the help of my daughter whom is the ‘nose’ of the family!). Marjoram isn’t as hardy as oregano and in particularly cold places is treated as an annual. Plant it in a sunny sheltered spot and it should see the winter through or even pot it up and bring it indoors during winter~ it is a perennial.
Greek Oregano origanum vulgaris hirtum

Image from Dimitrios Zervas
Now, how to tell the difference between true Greek oregano and your jo schmo oregano.. The flowers are white, not pink or purple and the flavour is so strong it will make your tongue go numb or at least tingle! It has a similar growth habit as origanum vulgare but not quite as invasive.
It’s a confusing world out there, because there are so many mix ups and it’s one persons word or image against anothers…so you’ve just got to find what you can, taste it, smell it, if you like it-grow it! But hopefully I’ve helped clear up some differences between the plants and you feel a bit more enlightened!
Share your thoughts!