232 FUNGOUS DISEASES OF PLANTS 



XXXI. HYPOCREACE^: 



In this family the mycelium is light or bright colored, never 

 dark, as is also the stroma when present. Perithecia are also 

 colored and vary from a buff or yellow to brown, red, or purple, 

 never black. They are usually more or less flask-shaped, free 

 upon the substratum, borne upon a mycelial weft (subiculum), 

 upon a stroma, or imbedded partially or completely in a stroma 

 (well-differentiated perithecial walls are absent in Claviceps, etc.). 

 The perithecium possesses a distinct ostiolum or mouth. The 

 asci are cylindrical or clavate fusiform. The spores (usually eight) 

 are diverse in form, and they sometimes bud within the ascus. Pa- 

 raphyses may be present. In general, the family is distinguished 

 from other pyrenomycetes only by color and texture. 



In this large family important pathological forms may be se- 

 lected from three genera, Neocosmospora, Nectria, and Claviceps. 



In Neocosmospora there is no true stroma. The colored peri- 

 thecia (buff or yellow to red) are clustered or scattered. They 

 possess pseudoparenchymatous walls and rather long ostiola. 

 The asci contain eight spherical, brown spores, with a distinctly 

 wrinkled surface. Conidia are present. 



In the genus Nectria the perithecia are yellowish to brown 

 or red, single or grouped, even varying as to the extent of 

 the stroma, which is, however, usually tuberculate or wart-like. 

 The asci are mostly cylindrical, bearing eight I -septate, usually 

 hyaline, elliptical spores. Conidia are common. 



Claviceps is characterized by the development of definite stro- 

 mata (sporophores) from a relatively large sclerotium, a stroma 

 consisting of a sterile stalk and a fertile head. Within the latter 

 (peripherally disposed) the asci are contained in flask-shaped 

 structures. There is no definite perithecial wall surrounding the 

 ascal conceptacle. The asci are more or less cylindrical and bear 

 eight hyaline, continuous, needle-shaped spores. 



Closely related to Claviceps may be mentioned the genus Cor- 

 dyceps, including some interesting and striking forms. The major- 

 ity occur upon insects, upon which they arc parasitic or saprophytic. 

 Two species are more or less common parasites of Elaphomyces, 

 a truffle-like, hypogeous genus. 



