Poisonous Plants of the Southern United States - Page 13 Poisonous Plants of the Southern United States sweet clover Melilotus sp. 2 m tall. Cultivated as a forage crop and soil builder. Under certain conditions, such as mold accumulation in the hay, coumarin, a harmless substance, is converted into dicoumarin. This compound interferes with the blood clotting mechanism, thus leading to hemorrhage.
Sheep are much more resistant to the effects of the toxic principle than are cattle.
Symptoms are related to massive blood loss. Swellings appear under the skin due to accumulations of blood. These swellings vary in size and may occur at any site on the body, but particularly in areas that are susceptible to bruising. Pale mucous membranes, rapid and weak pulse, and weakness are observed. Females may hemorrhage following calving.