TAXONOMY 
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known as mycorrhiza. Several species of the genus Tuber growing 
in woods of France, Germany and Italy produce tuberous subter- 
ranean bodies called Truffles, which are highly prized as a table 
delicacy by the inhabitants of these countries. 
Order 5. — Helvellales, the saddle fungi. Fleshy fungi entirely 
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. 
Fig. 93. — The morel, Morchella esculenla. (Gager, from photo by IV. A. Murrill.) 
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 
