The complex, flavorful, and inherently soothing bouquets found in cannabis are produced by terpenes, oils of the cannabis plant that are also responsible for many of the effects that make individual strains unique.
Terpenes come from the same glands that secrete cannabinoids like THC and CBD. As a genus, cannabis produces up to 150 different terpenes, though only 10 or so occur in significant concentrations. Their original adaptive purpose is much like that of other strong-smelling flora: to lure pollinators and repel predators.
There are two key types of terpenes: monoterpenes—or “light” terpenes—which evaporate easily and are destroyed in most shatter extraction processes, and sesquiterpenes—or “heavy” terpenes—which are more durable and likely to survive processing. In oil derived from outdoor-grown cannabis, monoterpene concentration ranges from 47.9–92.1% of the total terpenoid content, while sesquiterpenes make up anywhere between 5.2–48.6%. Myrcene, for example, is one of the most important (and most volatile) monoterpenes, believed to play a crucial role in the effects of cannabis. It’s not only one of the most common terpenes in popular cannabis strains, but often the most dominant. Due to the fragility and volatility of terpenes, heating them past their boiling point can severely undermine their healing properties and compromise your overall experience.
Apart from the diverse array of aromas and flavors, terpenes are fascinating for their ability to interact synergistically with other compounds. We have long understood that THC binds to cannabinoid receptors in the brain (where psychoactive effects are produced), but more recently, researchers have discovered that certain terpenes are able to bind to these receptor sites, as well. Terpenes that bind to receptor sites can affect their chemical output, modify the amount of THC passing through the blood-brain barrier, even alter the availability and rate of production of neurotransmitters like dopamine and serotonin. The effects produced by these mechanisms vary from terpene to terpene; some are especially good for relieving stress, while others promote focus and acuity. There are also many imperceptible physiological effects, including anticarcinogenic (i.e., cancer-fighting) and gastroprotective properties.
Their differences may be subtle, but terpenes add great depth to the horticultural art and connoisseurship of cannabis. Beyond their experiential and recreational effects, terpenes offer great medicinal value, and the limitless combinations of synergistic effects will likely open up new avenues for scientific and medical cannabis research.