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Ergot is caused by the fungus Claviceps purpurea, which affects rye, wheat and other cereal grasses. When first infected, the flowering head of a grain will spew out sweet, yellow-colored mucus, called "honey dew," which contains fungal spores that can spread the disease. Eventually, the fungus invades the developing kernels of grain, taking them over with a network of filaments that turn the grains into purplish-black sclerotia. Sclerotia can be mistaken for large, discolored grains of rye. Within them are potent chemicals, ergot alkaloids, including lysergic acid (from which LSD is made) and ergotamine (now used to treat migraine headaches). The alkaloids affect the central nervous system and cause the contraction of smooth muscle — the muscles that make up the walls of veins and arteries, as well as the internal organs.
http://www.luminet.net/~wenonah/history/ergot.htm
Type ergot witches into Google and you'll find a ton of stuff. Good luck on your paper!