ergot

n. disease of cereal grasses in which fungal growths replace healthy grains

Ergot is the common name of a fungus in the genus Claviceps that is parasitic on certain grains and grasses. The form the fungus takes to winter-over is called a sclerotium, and this small structure is what is usually referred to as 'ergot', although referring to the members of the Claviceps genus as 'ergot' is also correct. There are about 50 known species of Claviceps, most of them in the tropical regions. Economically important species are Claviceps purpurea (parasitic on grasses and cereals), C. fusiformis (on pearl millet, buffel grass), C. paspali (on dallis grass), and C. africana[1](on sorghum). C. purpurea can affect a number of cereals including rye (its most common host), triticale, wheat and barley. It affects oats only rarely.
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n. spur, ergot, lug

(n.)
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.
  

(n.)
See 2d Calcar, 3 (b).
  

(n.)
A stub, like soft horn, about the size of a chestnut, situated behind and below the pastern joint.
  

(n.)
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.
  

Noun
1. a plant disease caused by the ergot fungus
(hypernym) plant disease
2. a fungus that infects various cereal plants forming compact black masses of branching filaments that replace many grains of the plant; source of medicinally important alkaloids and of lysergic acid
(synonym) Claviceps purpurea
(hypernym) fungus
(hyponym) rye ergot
(member-holonym) Claviceps, genus Claviceps