222 THE FUNGI WHICH CAUSE PLANT DISEASE 



The order is very large, embracing according to Engler & PrantI 

 some eighteen families and over six thousand species. 



Eet to Families of Sphaeriales 



Perithecia free, either without a stroma, 

 partly seated in a loose mass of myce- 

 lium, or sessile above an imperfect 

 stroma 

 Walls of the perithecia thin and mem- 

 branous; asci soon disappearing 

 Perithecia always superficial, with 



copious tufts of hair at the mouth 1. Chaetomiacese. 

 Perithecia usually sunken, with only 



short hairs about the mouth 2. Sordaiiacete, p. 224. 



Walls of the perithecia coriaceous or car- 

 bonous 

 Perithecia either entirely free, or with 

 the base sUghtly sunken in the 

 substratum or stromatic layer 

 Stroma wanting or only thread-like 

 or tomentose 

 Mouths of the perithecia mostly in 



the form of short papillse. ... 3. Sphferiaces, p. 225. 

 Mouths of the perithecia more or 



less elongate, often hair-like. . 4. Ceratostomataces, 

 Stroma present p. 232. 



Stromata mostly well developed, 

 indefinite; perithecia in close 

 irregular masses, never flask- 

 like of funnel-like at the apex 5. Cucurbitariacese, p. 234. 

 Stromata small, sharp-bordered; 

 perithecia in rows or in regu- 

 lar rounded masses, flask- 

 shaped with funnel-shaped 



mouths 6. Coryneliacee. 



Perithecia more or less deeply sunken 

 in the substratum at base, free 

 above 

 Mouths of the perithecia circular in 



""tl'ne 7. Amphisphteriaceae. 



