| Noun | 1. | Claviceps - fungi parasitic upon the ovaries of various grassesfungus genus - includes lichen genera family Hypocreaceae, Hypocreaceae - family of fungi having brightly colored fleshy or membranous ascocarps; sometimes placed in its own order Hypocreales Claviceps purpurea, ergot - 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 |