282 TEXT-BOOK OF FUNGI 



important characteristics of the Tuberaceae. It is more 

 or less subterranean in habit, and has a continuous, more 

 or less globose peridium which permanently conceals the 

 hymenium from view. It has occupied a place in the 

 Tuberaceae until quite recently, when it was placed at 

 the commencement of the Discomycetes by Saccardo. 



PYRENOMYCETES 



KE Y TO THE FAMILIES 



Ostiolum or mouth, when present, circular. 



Perithecia produced singly, that is, not aggregated in 



a stroma, substance thin, membranaceous, or in some 



instances subcarbonaceous ; completely closed, hence the 



structure must decay or become irregularly torn before the 



spores can escape. Perisporieae. 



Perithecia produced singly or aggregated in a stroma, 

 substance membranaceous, coriaceous, or distinctly car- 

 bonaceous, blackish, quite distinct in structure from the 

 stroma, when the latter is present ; dehiscing by a definitely 

 formed opening or ostiolum. Sphaerieae. 



Perithecia scattered or aggregated in a stroma, fleshy or 

 membranaceous, not carbonaceous and frigid, generally 

 reddish, rarely bluish or yellowish-olive, with a distinct 

 ostiolum. Stroma, when present, rather soft and fleshy, 

 rarely byssoid. Hypocreae, 



Perithecia immersed in a stroma from which they are 

 scarcely or not at all differentiated; stroma cushion-shaped, 

 effused or linear, coriaceous or carbonaceous (not fleshy), 

 blackish (not brightly coloured); asci 4-8 spored, spores 

 hyaline, rarely tinged brown. Doihidieae. 



