Updated: Jul 10
Welcome to TerpeneHarvest™, the Higher Learning LV™ series that investigates a variety of terpenes produced by both cannabis and thousands of other plant species. This installment explores the terpene limonene and the plant species plectranthus amboinicus, better known as Cuban Oregano.
Plectranthus Amboinicus (Cuban Oregano). Copyright © Higher Learning LV
Most of us are middle class professionals who majored in one thing or another in college and show a propensity for a particular skill niche, such as engineering, management, or writing. When we began using cannabis, we may have perceived it to be healthy or lifestyle enhancing, but we probably didn't think that adopting a cannabis lifestyle would make us better botanists.
During the late summer of 2015, a friend and I attended a college town farmer's market where she found an interesting and didactic houseplant. It gave off no aroma. However, when the leaves were rubbed, a strong scent of lime was transferred onto one's fingers. In this particular plant, the odor was stronger than an actual lime, but so lime like that it defied description. The plant brought new meaning to the term essence.
After some investigation, it was learned that this succulent, fleshy herb was a plectranthus amboinicus variety, meaning it is easy to grow, from a southern climate (in this particular case, Honduras), and used mostly as a decorative plant.
Also known as "Cuban Oregano" and "cerveza 'n' lime," this herb can be used for a variety of purposes, from making a mild tea to treat digestive problems, respiratory ailments, and even arthritis to being used as a topical and rubbed on the skin as a cream to naturally repel insects.
Wrote Karen Lynn at Lil' Suburban Homestead:
"This herb is my very favorite right now because it propagates so easily and it has kind of a distinct intense lemony/lime taste…a great compliment to Mexican cooking and it has a property in it that helps to neutralize spice or capsicum."
Trichomes: Not Just for Cannabis
Because of what cannabis has taught me about the plant anatomy of resin-bearing herbs and flowers, I know that the "hairs" on the leaves of this Cuban Oregano sample are trichomes (resin glands). More than a dozen types of trichome glands appear in thousands of plant varieties, so they're versatile and vary in appearance and specific function.
I'm also certain that the source of the strong lime scent on my friend's plant (pictured above from her back deck) is these densely populated, nearly microscopic trichomes on the leaves that produce a variety of terpenes. Terpenes are simply chemicals, or molecules, that serve many purposes within the plant (chiefly the production and conveyance of aroma to fend off pests and predators).
In cannabis, trichomes are important due to their role in the manufacture of both cannabinoids and terpenes. Cannabinoids include that infamous euphoric seductresses, delta-8 and delta-9 tetrahydrocannabinol (THC), and another that eliminates seizures in epilepsy patients and carries significant medicinal promise, cannabidiol (CBD).
Terpenes, while famous for producing specialized aromas and available in nature in more than 20,000 varieties of plants, appear in cannabis in about 200 types. In fact, 10-30 percent of the resin produced by smoked cannabis is the result of terpenes. One of these terpenes, limonene, is—among other things—responsible for the lime aroma of some strains (cultivars/chemovars) of marijuana, as well as many other plants.
Limonene: Root Cause Found
Limonene is a terpene that conveys an odor of citrus, juniper, rosemary, or peppermint. It is a major part of what gives limes their citrus punch, as well as oranges, tangerines, lemons, and grapefruit. It is found throughout nature and in thousands of other herbs and plants. It appears in many strains of cannabis, as well as apparently in my friend's plectranthus amboinicus houseplant.
Limonene is a distinctive and special terpene that does much more than deliver aroma. It also aids in digestion, helps alleviate depression, and contributes anti-bacterial and anti-fungal properties (in this respect, it acts similarly to a cannabinoid). Probably most important, it is also known to fight cancer.
Dissing the Wine Snobs
I recall reading cannabis strain reviews in the past, in which reviewers referred to the aroma of the pot they were sampling as "pine needles with a hint of rosemary" or "very earthy, with coffee undertones and musk" or some such thing.
Just as with fine wines, I discounted most of these olfactory observations, thinking they were mostly the pompous perceptions of subject matter experts who had to find one way or another to turn their reviews into a respectable—and profitable—craft.
Copyright © Higher Learning LV
But I was wrong. On the surface, it may seem absurd that a strain of cannabis would smell like a completely different species of plant (such as a pine tree, juniper plant, or peppermint bush). But they do. Your takeaway > The source of that aroma—chemically speaking—is identical. Thus, a "piney" sample of cannabis and an actual pine tree gain their respective distinctive aromas from the same terpene molecule.
Of course, the final mix of terpenes is unique to not only each plant species, but also to each strain or subject. One Durban Poison cannabis plant will produce a unique terpene profile, just as humans sport different voices, intelligence levels, and eye colors.