294 



BOTANY: PRINCIPLES AND PROBLEMS 



comycetes or disc fungi is therefore often applied to the group. 

 The inner surface of the cup consists of a layer of asci and sterile 

 hyphae. Such a layer is known as the hymeniimi. These plants 

 are almost all saprophji:es and their brightly colored fruiting 



Fig. 169. — Peziza ciliata. 



The cup-like ascocarps, on the inner surface of which 

 the asci are borne. 



bodies are conspicuous on rotting legs, damp earth, and similar 

 situations. 



Related to the cup fungi are the Morels {Helvellales), which 

 develop large, fleshy, and edible fructifications, the fruiting 

 surface of which is broken up into irregular pockets; and the 

 Truffles {Tuber ales), which produce subterranean, tuber-like 

 ascocarps, usually associated with the roots of oak trees, and 

 much prized as delicacies. 



Fig. 170.- — Plowrightia morbosa, the "black knot" of plums and cherries. 

 Hard, black fruiting mass of the fungus on a twig which it has attacked. The 

 small dots are openings to the perithecia. 



2. Pyrenomycetes or Black Fungi. — Here are found a large 

 and varied group of fungi which include both parasitic and sapro- 

 phytic species. Their mycelium is often hard and compact and 

 is characteristically dark in color. The ascocarp consists of a 

 very small, flask-shaped structure, the peritheciu7n, lined with 



