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Free and bound coumarin are extracted by autoclaving leaf tissue in water. Free coumarin is determined directly from an aliquot of the water extract diluted in alkali. Additional autoclaving of the extract in concentrated alkali is required for release of the coumarin from the bound form, permitting an assay for total coumarin. Bound coumarin values are then obtained by difference. Results of the assay as applied to four different phenotypes of sweetclover are given.