The loss of coumarin from sweet clover leaf samples amounted to 70 to 75% when the samples were air-dried for 10 days and 21 to 51% when oven-dried at 175° F. for one hour. Fresh leaf material placed in 2.5 N NaOH and stored in darkness at room temperature showed no loss of coumarin over a six month period but when stored in light at room temperature losses were evident: in 10 days and very heavy after six months' storage. Coumarin content was maximum in flower buds and fresh leaves from the tip of branches. Root and stem tissue and the more mature leaves from the central and lower portion of the plants were very low in coumarin. A rapid qualitative procedure is described which involves collection of fresh young leaves and storage of them in 2.5 N NaOH in the dark until they are examined in ultraviolet light. Plants classified as coumarin-deficient by this procedure were found to be void of coumarin on photofluorometric analysis.