TAXONOMY 265 



saprophytic, living attached to leaf mold or growing in humous soil 

 or, in a few cases, on decaying wood. The fleshy fruiting bodies 

 (ascocarps) are divided into stalk (stipe) and cap (pileus) portions. 

 The external surface of the cap is covered, with a layer of asci and 

 paraphyses which together constitute the ascigeral layer. To this 

 group belong the Morels and the Earth Tongues. 



One of the Morels, Morchella esculenta, is frequently found .in 

 fire-swept woods. Its fruiting body consists of a hollow, externally 

 ridged stipe, bearing upon its summit a fleshy pileus whose outer 

 surface is honeycombed with ridges and depressions. The depres- 

 sions are covered with an ascigeral layer composed of asci and 

 paraphyses. This species is edible. 



Order 6. Pyrenomycetales, the mildews and black fungi common 

 as superficial parasites on various parts of plants. To the black 

 fungi division of this order the Ergot fungus, Claviceps purpurea 

 belongs. 



Life History of Claviceps Purpurea. Through the agency of 

 winds or insects the spores (ascospores or conidia) of this organism 

 are brought to the young ovaries of the rye (Secale cereale). They 

 germinate into long filaments called hyphae, which, becoming en- 

 tangled to form a mycelium, spread over the ovary, enter it super- 

 ficially, secrete a ferment, and cause decomposition of its tissue and 

 the resultant formation of a yellow-mucous substance called honey- 

 dew, which surrounds chains of moniliform reproductive bodies 

 known as conidia. The honey-dew attracts certain insects which 

 disseminate the disease to other heads of grain. 



The mycelial threads penetrate deeper and deeper into the ovary 

 and soon form a dense tissue which gradually consumes the entire 

 substance of the ovary and hardens into a purple, somewhat curved 

 body called a sclerotium, or official ergot the resting stage of the 

 fungus, Claviceps. 



The ergot falls to the ground and in the following spring sprouts 

 into several long stalked, globular heads called stromata or ascocarps. 

 Each (fruiting) head or ascocarp has imbedded in its surface nu- 

 merous flask-shaped invaginations called perithecia, from the bases 

 of which several sacs or asci develop. Within each ascus are 

 developed eight filiform spores (ascospores) which, when the ascus 



