Seaver: Hypocreales of North America 43 



Order HYPOCREALES 



Perithecia globose, ovate, conical, cylindrical, fusoid, or flask- 

 shaped, free on the substratum (occasionally subepidermal) or 

 united by a common matrix, varying from a cottony subiculum to 

 a distinct fleshy stroma, bright-colored, white, yellow, red, brown, 

 violet, but never entirely black, except in extreme age, opening 

 by an ostiolum ; perithecial wall membranaceous or submembra- 

 naceous, never carbonaceous ; stroma when present bright-colored 

 and soft, fleshy or cottony, and varying in size from 1-2 mm. to 

 several cm. in diameter, patellate or effused, with the perithecia 

 entirely superficial or partially to entirely immersed; asci cylin- 

 drical, clavate, or subovoid, mostly 4-8-spored but often becom- 

 ing 16-spored by the separation of each original spore into 2 

 globose or subglobose cells; spores simple or compound, hyaline 

 or colored, globose to filiform. 



Conidiophores and conidia very variable. 



Stroma wanting, or when present, with the perithecia entirely 



superficial, usually in cespitose clusters. i. Nectriaceae. 



Stroma or stromatic base always present and forming a con- 

 spicuous matrix in which the perithecia are partially to 

 entirely immersed, rarely subsuperficial especially in aged 

 specimens. 2. Hypocreaceae. 



Family 1. NECTRIACEAE 



Perithecia entirely free on the substratum (occasionally sub- 

 epidermal), or seated on a fleshy or tubercular stroma, but when 

 the latter is present, perithecia always superficial, usually in cespi- 

 tose clusters ; stroma often obscured at maturity by the perithecia 

 and occasionally becoming obsolete in aged specimens, but in such 

 cases its presence is indicated by the densely cespitose clusters of 

 perithecia. 



Stroma and stromatic base entirely wanting ; perithecia free 

 on the substratum, scattered or crowded, occasionally 

 subepidermal. 1. Nectrieae. 



Stroma or stromatic base always present ; but often obscured 

 at maturity by the perithecia and occasionally disappearing 

 in weathered specimens but its presence indicated by the 

 densely cespitose clusters of perithecia. 2. Creonectrieae. 



