Organic compounds that provide aroma and flavor in cannabis and a variety of other organisms, including plants. Terpenes are responsible for the aroma and flavors of cannabis, and influence its effects by interacting with cannabinoids. Terpenes are formed inside cannabis trichomes, and their relative presence is directly affected by both the spectrum and intensity of light exposure.

Scientifically speaking, terpenes are defined as “a large class of hydrocarbon compounds constructed from five-carbon isoprene units that are combined to produce a great variety of skeletons.” These basic molecular “skeletons” are “then acted upon by various enzymes to add functionality and altered oxidation,” processes that ultimately lead to the wide variety of effects produced by terpenes.

More About Terpenes

Terpenes are aromatic molecules responsible for the unique aroma of each cannabis cultivar. The appealing aromas and flavors we experience when we consume cannabis are all thanks to terpenes. Each cannabis cultivar has its own unique aroma because it has its own distinct terpene content. Whether you smoke cannabis flower, dab concentrates, or vaporize either, these molecules are hard at work delivering tasty citrus, diesel, woody, pine, skunky, coffee, spicey, herbal, or tropical flavors to your palate.

Scent has long been an accepted central indicator for the quality of cannabis flower. Cannabis cultivated and cured to the highest standards typically exhibits a pungent yet pleasant aroma. Flowers emitting a strong fragrance are commonly referred to as having a “dank” or “loud” odor, indicating the overall quality of the flower.

Aroma and flavor are subjective, and different aromas will appeal to different palates. There are a variety of terms for the types of aromas high-quality cannabis emits, including “skunky,” “diesely,” and “piney.”  The term “grassy” is often used to describe a smell that indicates low-quality flower, but a grassy aroma doesn’t necessarily denote poor quality. A distinct, pungent, and unmistakable aroma — regardless of its particular flavor — is evidence of terpenes hard at work within the cannabis plant.

So what does this mean for cannabis users? Basically, it gives merit to the idea that “the nose knows.” Our bodies and brains subconsciously have a preference for a particular terpene profile. 

Some people like fuel smells in their cannabis. Others prefer a fruity scent. In any case, shopping for cannabis based on scent may effectively lead the user to cultivars that best suit their needs. 

Other Terpene Sources and How They Compare to Cannabis

Terpenes are the primary components of essential oils — aromatics responsible for a plant’s regeneration, oxygenation, and immunity defense. Essential oils have been used for medicinal purposes for thousands of years, and extracted from a variety of plants and foods. 

There’s no recognizable difference, for example, between isolated caryophyllene from hops or from cannabis. However, there is a difference between the other compounds at play in cannabis compared with other plants. Further research is needed to know exactly how the remedial effects of cannabis terpenes compare with terpenes from other sources. What we have discovered is that cannabis terpenes support other cannabis molecules in producing desired effects.

Where Are Terpenes Found on the Cannabis Plant?

You’ve probably noticed the tiny glandular hairs that cover the surface cannabis plant, giving it a crystal-like sheen and sticky feel. They’re called trichomes, and they’re responsible for terpene production in cannabis. Trichomes contain resin glands that make terpenes and cannabinoids such as tetrahydrocannabinolic acid (THCA) and cannabidiolic acid (CBDA), which turn into tetrahydrocannabinol (THC) and cannabidiol (CBD), respectively, when decarboxylated. In other words, almost everything a user wants from cannabis, including terpenes, are found in trichomes all over the plant’s surface.

Terpenes vs. Terpenoids

As the popularity of these aromatic molecules has skyrocketed in the cannabis market, the terms terpene and terpenoid have become interchangeable. But there is a notable difference between the two. 

Terpenes are hydrocarbons — compounds made of hydrogen and carbon. When cannabis is dried and cured, terpene atoms are oxidized, and terpenes then become terpenoids.

Why Does the Plant Produce Terpenes?

Terpenes are created by plants to protect against herbivores, insects, and other environmental dangers. They’re also responsible for a plant’s regeneration and oxygenation. In light of these functions, it makes sense that some serve as potential immunity boosters in humans. It appears that terpenes are providing immunity defenses in both the people who consume these aromatic compounds and the plants that produce them.

More than 200 terpenes have been discovered in the cannabis plant, but most of them are only present in such extremely low quantities that testing labs aren’t even able to detect them. So why does the cannabis plant produce them all?

Current research indicates several factors that contribute to terpene diversity. Terpene synthases (TPSs) — enzymes responsible for creating the terpene structure — may either produce multiple terpenes from the same basic structure, or provide pathways for the production of whole new terpenes. 

It’s also possible that terpenes continue to diversify as part of an escalating defense against natural enemies that will evolve and diversify their counter-defenses in the future. Terpene diversity may also be a result of human intervention. Or, more accurately, the chemical differences we see in cannabis may be driven by extensive cultivation and breeding for a variety of desired traits.

How Growing, Harvest, and Curing Conditions Affect Terpene Expression

Terpene preservation has never been more important to the cannabis market than now. Growing, harvesting, and curing conditions all have an effect on terpene expression, and they can all contribute to the terpene-heavy cultivars that today’s cannabis consumers are looking for.

Growing cannabis plants indoors will give a grower greater control over environmental factors that either contribute to or take away from a plant’s terpene expression. Indoor growers will be familiar with hydroponics, or methods of growing plants in a system of nutrient solution and water instead of soil. 

While a hydroponic grow won’t necessarily inhibit terpene expression, growing in traditional soil is an easier way to ensure a prominent terpene profile. An excess of nutrients may also inhibit terpene expression, which growers can combat by reducing nutrient intake during the final week or two before harvest.

Growers who want to get a rich terpene profile out of their plants should neither harvest too early nor too late. Harvesting too early may cut trichomes off from full cannabinoid and terpene production, while harvesting too late may produce trichomes that have decreased in chemical potency, or broken off entirely. Properly ripe trichomes will be bold, distinct, and translucent on the plant’s surface, and they’ll be rich in terpenes.

Other factors to keep in mind when growing cannabis for terpenes include growing at sufficiently cool temperatures (77-80 degrees Fahrenheit, or 25-26.67 degrees Celsius, during the day and roughly 7-10 degrees Fahrenheit colder at night) and drying under sufficiently cool temperatures (between 65-75 degrees Fahrenheit, or 18.33-24 degrees Celsius) to reduce terpene evaporation. Lastly, being as gentle as possible with cannabis flower in every step of the cultivation process will increase a grower’s chances of coming up with a terpene-rich final product. 

How Terpenes Interact With the Human Body

Terpenes do more than provide flavor and aroma. They also support other cannabis molecules in producing desired effects. This is called the entourage or ensemble effect, and it’s the reason these aromatic compounds have become such a critical area of cannabis research. 

Whether consuming cannabis for personal or medical use, we all go to cannabis for the same thing — the effect. The entourage effect presents a reality in which the right cocktail of cannabis compounds will prove more potent and effective than an isolated compound.

Terpenes and cannabinoids may either exaggerate or suppress one another’s effects, depending on which combination is present in a given cultivar and how an individual responds to it. Mounting scientific evidence suggests that terpenes play a considerable role in not only tempering the intoxicating effects of THC, but also creating synergy with phytocannabinoids and even increasing their therapeutic value.

A huge factor in the cannabis industry’s current terpene boom is the growing popularity of dabbing — the act of inhaling vaporized cannabis concentrates through a temperature-specific heating method such as a dab rig, e-rig, or vaporizer. Dabbing concentrates at high temperatures typically results in a smooth, tasty cannabis vapor-rich in flavors. What many dabbers may not be aware of is the possibility that terpenes produce toxic chemicals when heated to high temperatures. 

According to a study from Portland State University, vaporizing terpenes at the high temperatures required for dabbing may produce the toxicants methacrolein and benzene, which have been linked to certain cancers. So, if you want to enjoy a flavorful dab without heating the terpenes to toxicity, dab at as low of a temperature as possible.

Prominent Terpenes

Although hundreds of different terpenes have been found in cannabis, only a select group of them are sufficiently present. These are the 11 most prominent terpenes in cannabis, along with their aromas, boiling points, and potential health benefits as shown in experiments on animals. 

Myrcene

Myrcene is one of the two most prominent terpenes in cannabis — the other being caryophyllene — meaning most cultivars on the market are dominant in one or both. It carries the signature “earthy” aroma found in most cannabis plants. Its boiling point is 332.6 degrees Fahrenheit, or 167 degrees Celsius. 

 Similarly to several other cannabis compounds, myrcene may be an effective anti-inflammatory. A 2015 study in cell-culture models indicated that myrcene may be helpful in treating osteoarthritis. Myrcene may also alleviate pain. 

Caryophyllene

Beta-caryophyllene is another predominant terpene found in cannabis. It has a boiling point of 266 degrees Fahrenheit, or 130 degrees Celsius. In addition to cannabis, caryophyllene is found in hops, cloves, and rosemary. It carries an herbal aroma synonymous with these plants. 

Like myrcene, caryophyllene has both anti-inflammatory and pain relieving properties, at least in animal models. 

Pinene

Pinene is one of the most commonly expressed terpenes in all of nature. Most famously found in pine trees and other conifers, pinene is also responsible for the “piney” aroma of certain cannabis cultivars. Pinene also has anti-inflammatory properties, and may help to protect from ulcers and improve airflow to the lungs. It has a boiling point of 311 degrees Fahrenheit, or 155 degrees Celsius.

Limonene

In addition to cannabis, limonene is most commonly found in citrus fruits, in which it provides that citrus smell. It has a boiling point of 348.8 degrees Fahrenheit, or 176 degrees Celsius. Limonene is commonly used in a wide variety of natural products, such as cleaning supplies and fragrances. It could also boost the immune system, alleviate heartburn symptoms, and even be used as a solvent to dissolve gallstones rich in cholesterol.

Terpinolene

Terpinolene boasts a fresh herbal-citrus aroma, and has a boiling point of 361.4-365 degrees Fahrenheit, or 183-185 degrees Celsius. It’s commonly found in plants known for pleasant fragrances, such as rosemary, conifers, lilacs, and apples. Human studies have identified terpinolene as a potential antioxidant, and animal studies have found it to have sedative properties. Terpinolene might eventually be used to decrease cell proliferation associated with cancer. 

Humulene

Humulene is common cannabis terpene that’s also predominant in hops. It’s also present in sage, clove, basil, black pepper, and ginseng, and carries a corresponding “hoppy” aroma. Research has indicated that humulene may be an effective topical anti-inflammatory and pain reliever. It has a boiling point of 222.8 degrees Fahrenheit, or 106 degrees Celsius.

Linalool

Linalool is found in rosewood, bergamot, coriander, rose, jasmine and lavender with a boiling point of 388.4 degrees Fahrenheit, or 198 degrees Celsius. It carries a very pleasant floral aroma, and is often used in soaps and perfumes. 

In addition to potentially reducing inflammation and inflammatory pain like several other terpenes, linalool has several unique potential health benefits. It’s been found to inhibit the growth of fungal infections outside the human body, particularly as they arise from the yeast infection candida. It also has anticonvulsant and sedative properties.  

Ocimene

Ocimene has a strong, sweet, herbal scent and a boiling point of 212 degrees Fahrenheit, or 100 degrees Celsius. It’s found in a wide variety of plant life, including mint, mangoes, basil, and orchids. Omicene can act as an anti-inflammatory, and may have antiviral and antifungal properties.  

Nerolidol

Nerolidol is characterized by a singularly woody aroma, and used in a wide variety of cosmetic and cleaning products. It has also been studied for its potential as an antifungal, antioxidant, anti-microbial, and anti-inflammatory agent. Nerolidol may even help other drugs penetrate the skin for more effective topical delivery.  It has a boiling point of 251.6 degrees Fahrenheit, or 122 degrees Celsius.

Bisabolol

Bisabolol has a mild floral scent, and is frequently used in fragrances and cosmetics. It has a boiling point of 307.4 degrees Fahrenheit, or 153 degrees Celsius. Bisabolol has long been thought to heal the skin. Animal studies have shown that bisabolol may specifically reduce skin inflammation.

Guaiol

Guaiol is found in guaiacum and cypress pine. It has a quintessentially piney aroma, and a boiling point of 197.6 degrees Fahrenheit, or 92 degrees Celsius. Guaiol has been identified as a potential antimicrobial, as well as an inhibitor of lung cancer cell growth. Guaiol is also a central component of essential oils in Xylopia sericea fruits that have potential antibacterial and antioxidant properties.   

Chemotypes

There is a staggering number of chemical phenotypes, or chemotypes, of cannabis out there. A cannabis chemotype represents the chemical profile of a cannabis plant, i.e., its cannabinoid and terpene ratios.

Chemotypes of Cultivated Varieties

Most cultivars on the market are predominant in either myrcrene or caryophyllene, or both. However, research into the chemotypes of today’s cultivars suggests that one cultivar does not necessarily express one unifying chemotype, but rather, may exhibit a spectrum of chemotypes. In other words, two plants of the same cultivated variety may have slightly different chemical expressions. These findings actually tell us a lot about the obsolescence of our current cannabis taxonomy — namely, the indica/sativa/hybrid classification model.

The terms indica and sativa were originally used to describe a cannabis plant’s physical traits and geographic origin, not its chemical makeup. Furthermore, the indica/sativa taxonomy was established long before we knew anything about cannabis terpenes and the enormous variety of chemotypes implicated by their presence in the cannabis plant. Their inception also came long before intensive breeding utterly diversified the chemical makeup of the cannabis plant. 

A recent study on terpene and cannabinoid expressions in a wide range of plant samples concluded that a chemotaxonomic classification — or, more accurately, classifying cannabis by its terpene and cannabinoid contents — will be more effective in identifying the best medical uses for a given cultivar. 

Chemotypes of Landrace Varieties

A landrace is a cannabis plant grown in its native environment and geographical region. Acapulco Gold, Panama Red, Afghanistan, and Durban Poison are examples of original landrace strains of cannabis domesticated for traditional cultivation. Terpenes found in naturally occurring cannabis include myrcene, caryophyllene, humulene, limonene, and pinene. The common expression in landrace strains probably means they represent the terpene profiles that nature intended before humans started intensive breeding.

Products

Concentrates and Isolates

Concentrates have taken the cannabis world by storm in recent years, largely because of their terpene-rich contents and subsequent spectrum of juicy flavors. Cannabis concentrates isolate and accumulate all of the most desirable properties from cannabis trichomes — namely cannabinoids and terpenes — into one product. You may have either heard of or used full-spectrum extracts, sauce, or distillate. All of these are forms of cannabis concentrates.

Isolates, or extractions of a single cannabinoid or terpene, have also become more prominent in the arena of natural medicine. The possibility of individual terpene extraction as led to a variety of isolate products that aim to reap specific medicinal benefits. 

Re-infusion

Terpene extraction isn’t only exploited to create isolates. Once extracted, natural terpenes are also re-infused into cannabis goods, primarily for flavor. Oil cartridges — containers with a mouthpiece filled with concentrated cannabis for use with batteries — often include re-infused terpenes. Because the process of making distillate for vape cartridges removes all of the natural plant terpenes, some extractors will blend terp sauce — a cannabis extract composed of over 50% terpenes — with raw distillate to produce strain-specific vape cartridges.