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In the absence of canopy-opening disturbances, upland oak forests in the eastern United States are shifting to shade-tolerant, fire-sensitive tree species (i.e. mesophytes) via a hypothesized positive feedback loop of less flammable, self-promoting conditions, termed mesophication. To evaluate species-specific impacts on mesophication, I quantified canopy, bark, and leaf litter traits of five hypothesized mesophytes [red maple ( Acer rubrum ), sugar maple ( A. saccharum ), American beech ( Fagus grandifolia ), hickory ( Carya spp.), and tulip poplar ( Liriodendron tulipifera )] and four upland oaks [black oak ( Quercus velutina ), chestnut oak ( Q. montana ), scarlet oak ( Q. coccinea ), and white oak ( Q. alba )] in central Kentucky. Red maple, sugar maple, and American beech had increased canopy depth with stem size, smoother bark, and small, thin leaves when compared to oaks. My findings suggest that some mesophytes, such as red maple, sugar maple, and American beech, may decrease future forest flammability by reducing understory light and increasing fuel moisture.