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 
