Claviceps purpurea

Ergot Er"got, n. [F. ergot, argot, lit., a spur.] 1. A diseased condition of rye and other cereals, in which the grains become black, and often spur-shaped. It is caused by a parasitic fungus, {Claviceps purpurea}. [1913 Webster]

2. The mycelium or spawn of this fungus infecting grains of rye and wheat. It is a powerful remedial agent, and also a dangerous poison, and is used as a means of hastening childbirth, and to arrest bleeding. [1913 Webster]

3. (Far.) A stub, like soft horn, about the size of a chestnut, situated behind and below the pastern joint. [1913 Webster]

4. (Anat.) See 2d {Calcar}, 3 (b) . [1913 Webster]