Minnesota Plant Diseases. 



141 



insect molds, and hence are not, as far as is at present known, 

 of great economic importance. (Fig. 30.) 



Cup fungi (Discomycetes). These comprise one of the larg- 

 est groups of fungi. The range of habit and structure is very 

 great within the group. The cup fungi are very 

 closely related to the sphere fungi, as has al- 

 ready been pointed out. They are all sac fungi 

 and the sacs are always borne in structures com- 

 monly called cups. These cups may be con- 

 sidered as wide-mouthed spore-sac-capsules 

 such as are common in the sphere fungi. In the 

 early stages of many cup-fungi the cup is in fact 

 a sphere entirely closed or with a small pore-like 

 opening. The cups vary greatly in shape and 

 size. In many forms it is very minute and 

 requires a hand lens for its examination. In 

 others it is large, reaching six inches in diame- 

 ter and even exceeding this. Some forms are 

 like long goblets, while others resemble beakers 

 of all shapes. Many, again, are saucer-shaped 

 and some perfectly flat or even more or less con- 

 vex. Some are gelatinous in texture, others 

 cartilaginous or waxy, still others are more or 

 less leathery or simulate burnt wood. Few, if 

 any, have woody cups. They may be furnished 

 with hairs, sometimes with dense masses, and 

 often they have eye-lash-Hke, hairy spines lining 

 the edge of the cup. The cup is often a very 

 complex organ structurally and in a great ma- 

 jority of cases contains between 

 the sacs sterile threads of very 

 characteristic shapes. The sacs 

 are usually long cylinders and 

 line the inside of the cup with a 

 dense palisade, standing upright 

 in the cup — that is, at right angles to the inside surface. The 

 function of the sterile threads is probably that of assistance in 

 throwing out the spores. The sacs are often provided with 

 little lids at the apex and when the spores are ripe the lid comes 



Fig. 62. — A single sac and sterile threads 

 from the palisade of sacs of the 

 fungus shown in Fig. 61. The sacs 

 show eight spores. Highly magni- 

 fied. After Seavers. 



