Bract Expression

Bract expression refers to the prominence and density of floral bracts—the leaf-like structures that envelop cannabis flowers. Breeders classify strains along a spectrum from tight, compact bract coverage to looser, more visible calyx structures. This trait is genetically heritable and influences final flower appearance, trichome visibility, and structural integrity during development. Bract expression varies significantly across strain families, with some breeding lines consistently producing dense, resinous-looking flowers while others display more open architecture. Understanding bract morphology is fundamental to cannabis breeding selection, as it affects both aesthetic characteristics and practical cultivation outcomes like airflow and harvest efficiency.

Breeders select for bract expression to achieve desired flower density, bag appeal, and phenotypic consistency across generations. Tight bract expression is often prioritized in commercial breeding programs for visual marketability and perceived potency, while looser expression may be favored in breeding for specific terpene or cannabinoid research contexts.