Humic acids may alter carbon dioxide to methane emission ratios from wetland soils by serving as electron shuttles. Quinone moieties have been implicated as the active components in humic acids allowing electron transfer. We performed a modified serial extraction of humic acids from plant tissue and adjacent soil of ten wetland plant species varying in production of polyphenols and other plant aromatics to determine the influence of plant traits on soil humic acid composition and electron transfer potential. Yield of humic acids varied with both extract and plant species. We compared optical properties of humic acid extracts with those of polyphenols extracted directly from plant material to elucidate the importance of plant-derived components to humic acid composition. Both plant chemical composition and optical properties were compared to electron transfer potentials to determine whether specific compounds played a stronger role in determining electron transfer capacity. A subset of extracted humic acid substrates were added to soil incubations to directly test the hypothesis that electron shuttling can affect carbon dioxide to methane emission ratios. This work provides insight into plant and soil characteristics which may affect the importance of humic acids in influencing greenhouse gas emission in different ecosystems.