Type I Type Ii Type Iii Chemotypes

Cannabis chemotypes are classified primarily by their cannabinoid ratios, traditionally categorized as Type I (THC-dominant), Type II (roughly equal THC and CBD), and Type III (CBD-dominant). This classification system emerged from early cannabinoid research and remains widely referenced in breeding literature, though modern testing reveals more nuanced ratios exist across populations. Type I plants typically express higher THC with minimal CBD, Type II expresses meaningful levels of both cannabinoids, and Type III expresses higher CBD with trace THC. These distinctions reflect genetic predispositions controlled by multiple loci, including the well-documented CBDA/THCA synthase genes. The chemotype framework helps breeders track inheritance patterns and select parents for specific cannabinoid profiles across generations.

Breeders use chemotype classification to predict offspring cannabinoid expression and identify parent plants for targeted breeding goals. Understanding chemotype genetics allows selection for desired ratios in controlled crosses, though environmental factors and measurement variability can influence phenotypic expression.