YELLOW SWEET CLOVER
Melilotus officinalis

Location
South of Research Building wall. Numerous plants line the path to the helicopter pad.

Description
Yellow sweet clover has fragrant leaves; when crushed or dried they give off the scent of new-mown hay.   The yellow flowers are in racemes that are about two to four inches long.  Each leaf is divided into three leaflets and finely toothed.  Yellow sweet clover stands three to eight feet high, and can be seen from late spring to fall (Newcomb 1977).

History
Yellow sweet clover was used by Henry VIII, which led to the common name King’s Clover.  The Tudor farmers detested it because it overran pasturelands and damaged their corn (Griggs 1991).

Yellow sweet clover has been cultivated for forage, hay, and pasturelands. It has also been used to improve soil; the roots help to prevent erosion and fix nitrogen in the soil through numerous nitrogen-fixation nodules.  The seeds were once substituted for Tonka beans and the roots were eaten by Kalmuks.  Yellow sweet clover was also used for honeybee pastures and as a moth repellent (Duke 2001).

Hemorrhagic disease in cattle in the late 19^th century was traced to spoiled hay made from yellow sweet clover and acted on by Aspergillus mold. In 1889, Link and Campbell named the hemorrhagic agent dicoumarol. Dicumarol was first tested as a rat poison and then began to be used to treat heart attacks in humans in 1943. Dicumarol was the drug model for warfarin (also first tested as a rat poison)! Warfarin was first tested in humans in 1953, and remains an important, widely used anticoagulant drug today. (Mueller 1994)

Yellow sweet clover has also been used for symptoms of chronic venous insufficiency, varicose veins, thrombophlebitis, hemorrhoids, post-thrombotic syndromes, and lymphatic congestion (Duke 2001).  Additionally, it has been used as an anticoagulant, diuretic, laxative, stimulant, and tonic.  When smoked, it has been used for asthma (Duke 2001, Foster 1990).  Dried, the whole plant has been used in tea for neuralgic headaches, painful urination, gastrointestinal conditions, and aching muscles.  Topically, as a poultice, it has been used for inflammation, ulcers, wounds, and rheumatism (Foster 1990). 

Sweet clover has also been used in foods. In France, sweet clover is used in stuffing for rabbits. Gruyère and Sapsago cheeses, made in  Switzerland, are flavored with the flowers and seeds of sweet clover. The roots are cooked and eaten in Iceland. And throughout Europe, leaves and flowers have been used to flavor soups, stews, and marinades (Kiple 2000).

Current Medicinal Uses
Yellow sweet clover is not a commonly used medicinal herb today, but played a crucial role in the development of the widely used anticoagulant drug warfarin (see History).

References
Duke JA. Handbook of Medicinal Herbs. CRC Press, Boca Raton, 2001.

Elias TS, Dykeman PA. Field Guide to North American Edible Wild Plants. Outdoor Life Books, New York, 1982.Kiple KF, Ornelas KC, ed. The Cambridge World History of Food. Cambridge University Press, Cambridge, 2000.

Foster S, Duke JA. Eastern/Central Medicinal Plants. Houghton Mifflin Company, Boston, 1990.

Griggs B. Green Pharmacy. Healing Arts Press, Rochester, 1991.

Kiple KF, Ornelas KC, ed. The Cambridge World History of Food. Cambridge University Press, Cambridge, 2000.

Mueller RL, Scheidt S. History of drugs for thrombotic disease: discovery, development, and directions for the future. Circulation 1994;89:432-449.

Newcomb L. Newcomb’s Wildflower Guide. Little, Brown and Company, Boston, 1977.