Because the National Garden Bureau has declared 2012 as the Year of Herbs, I have decided to address an issue that has been in the back of my mind for quite some time, the difference between oregano and marjoram.
These similarly looking plants are not only both from the mint family of plants, they are also from the same genus, Origanum. Some would say these two culinary herbs taste the same, but others would disagree, particularly chefs and cooks who use them in entirely different dishes.
Oregano (Origanum vulgare), is widely known as an Italian herb, often used in pizza and pasta sauce recipes. Rub a few leaves of the plant and the fragrance is peppery and pungent. Some would say it also has a hint of lemon, although I've never noticed this.
Marjoram is a much milder herb, less peppery and sweeter than its cousin. Some cooks might substitute marjoram for oregano in a dish because they are so closely related, especially when using fresh herbs. When dried, the oils in the herbs are more concentrated, making it easier to tell them apart.
With more than 44 varieties of oregano, it's easy to get confused as to what to buy and what to use.
True oregano originated in Europe. The most common variety used in cooking is Greek oregano. Another seasoning, commonly called Mexican oregano (Lippia graveolens), isn't an oregano at all, but it is more spicy and is used in chili powders.
Common oregano is a perennial and is hardy to our climate. It prefers full sun, is easily grown from seed, and isn't particular about the type of soil it lives in. It also grows well in containers and makes a good windowsill kitchen herb, as long as it's in a sunny window.
Marjoram, (Origanum majorana), often called sweet marjoram is so closely related to common oregano, it, too, is easy to grow both in the garden and in containers. Because it has a milder flavor, marjoram is preferred in soups, salad dressings and meat marinades.
Still, many people can't tell the difference between the two plants. To really be able to distinguish between the two, hold a bruised or torn leaf of each plant up to your nose for a few seconds. After comparing the two, the differences in their fragrance will be more evident.
It isn't as easy to tell the herbs apart in their dried form, but the plants have differences that help to identify them in the garden center. Oregano is taller, nearly 2 1/2 feet tall and 2 to 3 feet wide when mature. The leaves are small, about an inch and a half across, are oval-shaped and hairy. It has purple stems and pinkish-purple flowers.
Sweet marjoram is a smaller plant, only about 12 inches tall and more bushy than common oregano. It also has oval shaped leaves, but the flowers are white and the plant is more delicate than its hardier cousin.
I have grown both herbs in my garden, as well as the more ornamental Golden Oregano, which is a variety of the herb, but much milder by comparison.