Hemp is not what it used to be. Once dismissed as rope and rags, the hemp plant is now being redefined not just by its industrial potential but by its cannabinoid chemistry. To truly understand hemp and how it fits into modern cannabis science, we need to talk about chemotypes.
A chemotype refers to the plant’s chemical profile, particularly the dominant cannabinoids it expresses. In cannabis, chemotypes are categorized into five primary groups. These classifications help breeders, scientists, and regulators differentiate between types of cannabis, including hemp, based on the ratio of cannabinoids like THC, CBD, and emerging compounds such as CBG.
Understanding THC vs THCA: Legal Definitions Meet Biochemistry
Before exploring the chemotypes, it is essential to understand the legal and biochemical distinction between THC and THCA.
THC (delta 9 tetrahydrocannabinol) is the active, intoxicating compound regulated under U.S. law.
THCA (tetrahydrocannabinolic acid) is its acidic precursor. It is non-psychoactive in its native form and must be decarboxylated, typically through heat, to convert into active THC.
Under the 2018 Farm Bill, the legal definition of hemp is based on delta 9 THC content alone, specifically less than 0.3 percent THC by dry weight. The law does not currently restrict THCA, even though it converts to THC when smoked, vaporized, or heated.
This distinction reflects a scientific fact about the molecule. As a result, cultivars that express high levels of THCA but remain under 0.3 percent delta 9 THC are considered federally compliant hemp under the 2018 Farm Bill, though enforcement and definitions vary by state.
The Biochemistry of Chemotypes: A Pathway from CBGa
At the biochemical level, all cannabinoid diversity begins with cannabigerolic acid (CBGa), often called the “mother cannabinoid.” CBGa is the central precursor molecule that can be transformed by different enzymes into three major acidic cannabinoids:
THCa synthase converts CBGa into THCa
Author: James Loud / High Times
