Claviceps Tul.; anamorph Sphacelia Lev.
Resting structures (sclerotia) large, elongated, dark brown, usually leathery, developing from host inflorescences.
Anamorph developing on the surface of the resting structures, accompanied by sugary secretions (honeydew). Conidiophores poorly-developed, hardly distinguished from vegetative mycelium, hyaline, branched. Conidiogenous cells in small clusters, flask-shaped, producing conidia successively from single apical conidiogenous loci.
Ascostromata produced from resting-structures after overwintering, long-stalked, brightly coloured, with a ± spherical head. Ascomata perithecial, usually ovoid, thin-walled, brightly coloured. Asci cylindrical, conspicuously elongated, with a glassy apical cap penetrated by a narrow pore. Ascospores usually helically coiled, filiform, multiseptate, ± hyaline, usually breaking apart into part-spores.
Claviceps species have been well-known since early times as ergot fungi, the fungus infecting cereals and causing serious illness and death for those eating infected grain. More recently, there has been intense research into the use of metabolites produced by Claviceps species in the pharmaceutical industry. See Mantle (1975) for a review of this subject. Similar useful metabolites are produced by endophytic relatives of Claviceps, by Epichloe and by fungi referred for convenience to the form-genus Acremonium. The relations between these fungi and their hosts, and the evolutionary implications of toxin production, are discussed by Clay (1988).