50 



PERISPORIALES 



Key to Families 



A. Asci borne on branched hyphae, hence irregularly 



disposed or in corymboid clusters 



B. Asci in a basal umbel or sometimes solitary 



1. Aerial mycelium typically present; no erumpent 



stroma 



a. Aerial mycelium white; appendages present 



and usually modified 



b. Aerial mycelium dark, sometimes lacking; ap- 



pendages usually absent 



(1) Perithecia not radiate; asci basal 



(a) Hyphae not slimy, straight-walled; peri- 



thecia parenchymic, the cells polyg- 

 onal, not slimy 



(b) Hyphae straight-walled; perithecia dis- 



solving in slime as they mature 



(c) Hyphae constricted or dematioid,, or in 



slimy skeins when straight-walled; 

 perithecia of rounded cells or agglu- 

 tinate straight-walled meridian hyphae 



(2) Perithecia radiate; asci hanging from the 



apparent tip 



2. Aerial mycelium lacking; perithecia borne on an 



innate-erumpent stroma, elongate 



Eurotiaceae p. 50 



Erysiphaceae p. 52 



Perisporiaceae p. 53 

 Englerulaceae p. 55 



Capnodiaceae p. 56 

 Trichothyriaceae p. 58 

 Coryneliaceae p. 58 



As a rule, the Eurotiaceae can not be distinguished externally from Perispo- 

 riaceae, and it is necessary to appeal to the origin or arrangement of the asci. In 

 young or fresh material this can usually be determined positively; in mature or 

 dry specimens it is best decided by the presence or absence of the umbellate arrange- 

 ment typical of the other families. The first four of these are most intimately 

 related and might well be treated as subfamilies of Perisporiaceae. Probably the 

 greatest dif^culty is met in separating the latter from the Capnodiaceae, the polyg- 

 onal parenchyma-like cells of the perithecia of the one offering the best criterion, 

 in contrast to the rounded cells or meridian hyphae of the other. The Tricho- 

 thyriaceae are more sharply set of? by the radiate wall of the perithecium, and the 

 Coryneliaceae by the innate-erumpent stroma and the coriaceous or carbonous 

 elongate perithecia. 



The Perisporiaceae have probably been derived from the Eurotiaceae, and have 

 constituted the central group from which all the others have arisen. The highly 

 developed appendages of the Erysiphaceae and the reduced number of asci suggest 

 that they are more specialized rather than the primitive forms of the order, though 

 their development favors the latter view. The other families also represent divergent 

 phyla, two of them, Englerulaceae and Coryneliaceae, ending blindly, while the other 

 two connect with higher groups, the Trichothyriaceae with Microthyriales, and the 

 Capnodiaceae with Sphaeriaceae, as do the Perisporiaceae likewise. 



Family 19. EUROTIACEAE 



1:24, 9:371, 11:253, 14:462; 16:398, 17:524, 22:25, 24:226; Lind. 1:1:297; TS 15:447 



Mycelium abundant, superficial or innate, usually saprophytic, mostly straight- 

 walled and without hyphopodia or spines; perithecia typically on the mycelium, 

 the wall usually parenchymic and membranous, consisting of polygonal plates as 

 a rule, breaking up generally or at the tip when mature, ostiole present only in 

 Micrascus, appendages present or lacking; asci typically in corymboid clusters on 



