Oreganos Part II
The August 2024 newsletter included an article on some of the more popular Mediterranean culinary oreganos, but the world of oregano includes so much more! This month I want to focus on two lesser known oreganos, commonly called ‘Mexican Oregano’. Common names for plants can get us in trouble, and here is the perfect example where knowing the botanical name is important so you grow the correct plant for your culinary use.
The most popular ‘Mexican oregano’ is Lippia graveolens. It is closely related to Aloysia triphylla (formerly Lippia citriodora), commonly called lemon verbena. It even looks similar in its growth habit and small white flowers, and the fact that it very rarely produces seed. It grows somewhat large, to 4 ft tall, and will be a bit lanky if you don’t pinch it back frequently. Of course you will, because you will be cooking with it often! The leaves are small, rounded and grayish green or sometimes lime green, and somewhat rough feeling. Lippia graveolens is native to the southwestern US and northern Mexico. It thrives in full hot sun and soil with good drainage. Once established it is drought tolerant and the flavor will intensify if you maintain the plant with just occasional deep watering. It is considered a tender perennial – a light frost will defoliate the plant, but hard freezes will kill the plant, including the roots. If you live where temperatures drop below 28 degrees you will want to keep the plant in a container so you can protect it during the winter, or treat it as an annual, harvesting the entire plant in the fall and drying the leaves for winter use.
The second plant commonly grown as ‘Mexican oregano’ is Poliomentha longiflora. It looks very different from Lippia graveolens. Poliomentha has smooth, dark green leaves on a compact lush looking 3 ft shrub, covered with long tubular shaped lavender flowers that hummingbirds love. Poliomentha does very well in morning sun, afternoon shade conditions, is drought tolerant and deer resistant, and is a bit more cold hardy. It tends to be evergreen in our climate, so is a great culinary source all year if you want to cook with it during the winter. It is also smaller and more attractive in the garden. Poliomentha is native to Texas and Mexico.
So, what’s the difference? Usually when you buy dried ‘Mexican oregano’ in the store in a plastic bag or container, you are purchasing Lippia graveolens. This is the hotter, spicier flavored species that has a hint or undertone of citrus and a bit of heat on the tongue. Poliomentha longiflora is less hot and spicy, and has a bit of mint and rosemary to the flavor. One of its common names is rosemary mint, and Poliomentha definitely has the flavor of both, plus a complex oregano flavor forward.
If you look these plants up online, you will see that neither is easy to find. We lost our stock plant of Lippia graveolens 2 years ago and had to rebuild our stock from 3 little plants. Now, we have plenty to sell and stock plants growing in the ground and in the greenhouses for back up. Poliomentha has been easier to maintain in the garden, so we always have stock of that plant! Because neither plant reliably produces seed, growing from cuttings is the best method to produce new plants. Using small 2 inch tip cuttings in a very well drained mix and keeping the cuttings well misted will produce new plants, usually in 8-10 weeks. It’s a slow process to get new plants, but very rewarding!
Although many people choose just one of the Mexican oregano species to grow, I suggest growing both so you can compare flavors and enjoy their beauty!