Tall Coreopsis

Giant Cutleaf Coneflower and Tall Coreopsis both form large clumps and compete for space, nutrients, and light.

Sunflowers produce strong allelopathic compounds that inhibit growth of other tall Asteraceae including Coreopsis species

Tall coreopsis can shade out smaller composites, and both species may produce allelopathic compounds

Congeneric coreopsis species compete for similar resources, with tall species potentially shading shorter ones

Tall Asteraceae species compete for similar light conditions and soil nutrients in prairie environments