THC-Dominant, CBD-Dominant and Mixed Chemotypes

A chemotype is a plant's chemical type. In cannabis the most useful grouping is not "indica" or "sativa" but which of two compounds, THC or CBD, the plant makes more of. This page explains the three categories and how they relate to the word hemp. For the difference between a cultivar, a chemotype and a strain name, see cultivars, chemotypes and strain names. This is education only, not medical or legal advice.

The three chemotypes

Researchers describe cannabis as falling into three broad groups based on the dry-weight ratio of THC to CBD. [1][2] The three-type framework is established across the studies read. The numbers inside each type are not.

The cut-off ratios used to assign a plant to a type differ between studies. We did not read one agreed numeric standard, so none is given here. Which chemotype a plant belongs to is a measured result on a specific plant or batch, not a name on a package.

Why the mix happens: the genetics

Both THC and CBD are made from the same starting compound, cannabigerol (CBG). The 2004 chemotaxonomy study explains that two gene variants (alleles) code for enzymes that convert CBG to CBD or to THC. [1]

A classic breeding study crossed plants that make pure CBD with plants that make pure THC. Every first-generation offspring was the mixed type, and the next generation split into pure CBD, mixed and pure THC in a 1:2:1 pattern. The authors proposed one gene with two co-dominant alleles, which is why mixed plants appear when both are present. [4] Real-world cannabis can be more complicated, and this describes one study's model.

What this looks like in commercial cannabis

In a public dataset of legal cannabis from Washington state, products fell into three broad chemotypes defined by the THC:CBD ratio. [2] A 2022 analysis of 89,923 flower samples from six states describes THC-dominant (Type I) cultivars as predominant in the commercial market, because breeding has focused on them. [5] A 2018 review makes a similar point, noting that Type I is the prevalent offering in both medical and recreational markets. [3]

Within each chemotype, other compounds still vary. In the 2022 analysis, THC-dominant samples with different Indica, Hybrid and Sativa labels were highly intermingled in terpene profile, so the labels did not separate them. [5]

Chemotype and the word "hemp"

Chemotype and hemp are related but not the same idea. A chemotype describes the balance between THC and CBD. "Hemp" is a legal and agricultural category based on a measured THC limit.

• NCCIH notes that some cannabis plants contain very little THC and, under US law, are considered "industrial hemp" rather than marijuana. [6]
• A US federal statute defines hemp as the plant Cannabis sativa L. with a delta-9 THC concentration of not more than 0.3 percent on a dry weight basis (text read 2026-10-22). A 2025 amendment, effective 365 days after November 12, 2025, changes the measure to total tetrahydrocannabinols including THCA. [7]
• Genetically, a 2015 study found hemp and drug-type (marijuana) samples are distinct genome-wide, not just in THC genes. [8]

Whether a particular plant or product counts as hemp depends on the law that applies where it is, and its measured THC. Laws change, and this is not legal advice. See hemp legal definitions and hemp vs marijuana.

Why chemotype is still not a guide to effects

Chemotype tells you which major cannabinoid dominates, which is far more relevant than an indica label. It still does not give a personal dose or effect. THC is the compound mainly responsible for the effects on mental state, [6] and NCCIH reports that CBD may have side effects, that CBD use has been associated with liver injury and drug interactions, and that some effects appear to be due to CBD itself. [6] See THC, CBD and CBD and medication interactions.