General: sweet-smelling herb, 50-300 cm tall. Growth habit: erect annual or biennial from strong taproot, often growing in colonies. Stems: freely branched above, hairless or with sparse, fine, flat, stiff, very short hairs.
Leaves: alternate, divided into 3 leaflets, elliptic to oblanceolate or oblong, 1.5-3 cm long, with small, sharp teeth almost to the base, almost hairless to finely flat-short-hairy. Terminal leaflet with short stalk. Stipules linear, partially joined to the leaf stalk.
Flowers: yellow, 4-6 mm long, numerous in tall, narrow clusters, 3-10 cm long, from leaf axils. Calyx teeth almost equal, narrowly lance- to awl-shaped.
Fruits: pods, ovoid, slightly longer than the calyx, 3-4 mm long, with raised, netted veins, dark brown when mature, staying closed, usually with 1 seed.
Disturbed or cultivated ground, along roadsides, in most parts of MT. Introduced from Europe, widely distributed as a weed over much of the U.S. and Canada.
The root of yellow sweetclover was consumed as a food by the Kalmuks. Young shoots can be cooked and used like asparagus. Young leaves can be eaten in salads and the leaves and seedpods cooked as a vegetable. They have also been used as a flavoring. Only fresh leaves should be used since the dried leaves can be toxic. This is possibly due to the presence of coumarin, the substance that gives some dried plants the smell of new mown hay. The flowers, raw or cooked, are edible. The flowers and seeds can be used as a flavoring. The flowers also give an aromatic quality to some tisanes.
Melilot, used either externally or internally, can help treat swollen and twisted veins and hemorrhoids though it requires a long-term treatment for the effect to be realized. Use of the plant also helps to reduce the risk of phlebitis and thrombosis. Melilot contains coumarins and, as the plant dries or spoils, these become converted to dicoumarol, a powerful anticoagulant. Thus the plant should be used with some caution, it should not be prescribed to patients with a history of poor blood clotting or who are taking warfarin medication. The flowering plant is antispasmodic, aromatic, and has agents that relieves and removes gas from the digestive system, that induces urination, that softens and soothes the skin when applied locally, and agents that induces the removal (coughing up) of mucous secretions from the lungs. It is mildly sedative and has agents that help in healing wounds, fresh cuts, etc., usually when used as a poultice. A tea has been used in the treatment of sleeplessness, nervous tension, neuralgia, palpitations, swollen and twisted veins, painful congestive menstruation, in the prevention of thrombosis, flatulence and intestinal disorders. Externally, it is used to treat eye inflammations, rheumatic pains, swollen joints, severe bruising, boils and erysipelas, while a decoction is added to the bath-water. The flowering plant is harvested in the summer and can be dried for later use. A distilled water obtained from the flowering tops is an effective treatment for conjunctivitis.
The leaves contain coumarin and they release the pleasant smell of newly mown hay when they are drying. The leaves can be dried and used as an insect repellent, especially in order to repel moths from clothing. They can be put in pillows, mattresses etc. Poorly dried or fermented leaves produce a substance called dicoumarol. This is a potent anti-coagulant which is extremely poisonous in excess, it prevents the blood from coagulating and so it is possible to bleed to death from very small wounds. Dicoumarol is used in rat poisons. The plant can be used as a green manure, enriching the soil with nitrogen as well a providing organic matter.
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