Narrow Leaf Morphology

Narrow Leaf Morphology describes cannabis plants with distinctly thin, elongated leaflets relative to the width-to-length ratio typical of broad-leaf varieties. This trait appears across multiple genetic backgrounds and is often associated with sativa-dominant lineages, though it can occur in hybrids and indica-influenced plants. Narrow leaves typically contain fewer mesophyll cells and show reduced surface area, which may influence light penetration and transpiration patterns during cultivation. Breeders have documented this morphology in heirloom and modern cultivars, with lineage records frequently reporting narrow-leaf expression in equatorial and tropical adaptation lines. The trait's heritability is polygenic, meaning multiple genes contribute to the final leaflet width phenotype.

Breeders working in sativa-forward or landrace restoration projects often select for or document narrow-leaf morphology as a marker of genetic origin or environmental adaptation. Understanding this trait helps distinguish between phenotypic plasticity (environment-driven leaf shape changes) and stable genetic expression when stabilizing or creating new cultivars.