Narrow Leaf Phenotype

Narrow leaf phenotype refers to cannabis plants displaying characteristically thin, elongated leaflets—typically associated with sativa-dominant genetics or equatorial landrace origins. This morphological trait is distinct from broad-leaf phenotypes and reflects adaptations to specific growing conditions, historically linked to regions with intense sunlight and high humidity. Narrow leaves may present reduced surface area for transpiration and can influence light penetration through the canopy. The phenotype is inherited through multiple genes and can appear across hybrid crosses, though it tends to express more consistently in sativa-type cultivars. Breeders often observe narrow-leaf expression as a marker of specific ancestry or environmental adaptation rather than a singular trait.

Narrow leaf phenotype serves as a visual marker for breeders tracking sativa lineage or landrace genetics in hybridization programs. Growers sometimes select for or against this trait based on cultivation method, as leaf morphology can influence airflow, light distribution, and overall plant architecture in different environments.