MILDEWS AND RELATED FUNGI 1 63 



are thin and membranaceous to coriaceous, slightly transparent to 

 black and opaque. The asci are usually very delicate, surrounded 

 by long paraphyses, or intermingled with them. The dark-colored 

 spores are one- to many-celled, surrounded by a hyaline gelatinous 

 envelope, or ornamented with hyaline gelatinous spicula. The 

 SoRDARiACE^ are entirely saprophytic and grow on manure, hence, 

 they are coprophilous fungi. Special mechanical devices are shown by 

 the asci for eruptive spore discharge and the distance to which the 

 spores are shot may be between 5 and 9 cm.^ 



Family 4. Ch^etomiace^. — This is a small family of two genera, 

 ChcBtomium and Bommerella, which are found on waste paper, manure 

 and on small living fungi, which resemble the fungi of the family 

 PerisporiacecB, if the mouth to the perithecium is wanting. Bom- 

 merella has three-cornered ascospores. The perithecia of such forms 

 as ChcBtomium spirale and C. crispatum are provided apically with 

 masses of spirally wound ha^'rs. 



Family 5. Sph^riace^. — This important family includes parasitic, 

 or saprophytic fungi showing exceptional diversity on dead parts. 

 They have rounded perithecia with definite opening. The peridium is 

 evident, mostly dark-colored, membranous to leathery never fleshy, 

 usually free from the substratum, or more or less depressed. A 

 stroma may or may not be present. Some authors include a number 

 of families which perhaps may be subordinated here and ranked as 

 subfamilies. Rosellinia quercina is a disease of oak seedlings. Myco- 

 sphcerella fr agarics is the cause of leaf spot of strawberry; M. strati- 

 formans produces leaf-splitting blight of sugar cane. Gulgnardia 

 Bidwellii is a most important parasite, being responsible for the black 

 rot of the grape and G. vaccinii causes cranberry scald. Apple 

 scab and pear scab are due to the attack of Venturia pomi and Venturia 

 pyrina. A serious disease of sycamore leaves in the spring known as 

 anthracnose is caused by Gnomonia veneta. 



Family 6. Valsace^. — The stroma of these fungi is black and is 

 formed in the substratum which is more or less altered. The peri- 

 thecia have a regular border and take various forms in the different 

 genera. The asci are cylindric and long-stalked, alternating with 

 paraphyses. Pycnidiospores are formed in pycnidia and conidiospores 



1 Griffiths, David: The North American Sordariace^. Memoirs of the 

 Torrey Botanical Club, xi, No. i, May 7, 1901. 



