102 PHACIDIALES 



Order 11. PHACIDIALES 



Apothecia superficial, erumpent, or innate and then sometimes concrete with 

 the epiderm, elongate, elliptic or round, typically opening by a cleft or splitting into 

 lobes, usually dark, but light-colored in one family, varying in texture from car- 

 bonous to membranous, corious, corneous or waxy, but never fleshy or gelatinous, 

 separate or gregarious, occasionally cespitose or stromate; asci typically cylindric 

 and 8-spored, paraphyses regularly present, often forming an epithecium, filiform, 

 clavate or branched; hypothecium usually thin, well-developed only in one family; 

 spores various. 



The limits of this order have been somewhat extended in the present treat- 

 ment, owing to the practical difficulties in the way of defining the families sharply. 

 There has been general agreement as to the Stictidaceae owing to the light color 

 of the apothecium, but the genera with dark apothecia have been treated very 

 differently by Saccardo, Rehm, and Hoehnel. This is best exemplified by the 

 Hypodermieae, which are distributed among the families of his Phacidiales by 

 Hoehnel, placed in a separate family next Hysteriaceae by Rehm, and distributed 

 in this family by Saccardo. By virtue of their thick hypothecium, the Tryblidiaceae 

 may be placed almost equally well in the Pezizales, but they are retained here because 

 of the cleft or lobed opening. 



This order is considered to be diphyletic, the Hysteriaceae being derived from 

 the Sphaeriaceae and in turn passing directly into the cleft forms of Phacidiaceae 

 and perhaps Tryblidiaceae as well. The round apothecium as a rule appears to have 

 arisen from the ascoma of the Microthyriales, a number of genera placed by Theissen 

 and Sydow in the Stigmateae having been transferred to Phacidiales by Hoehnel. 



Key to Families 



A, Algal host-cells lacking 



1. Apothecia dark 



a. Apothecia opening by a narrow cleft Hysteriaceae p. 102 



b. Apothecia opening by lobes or a wide cleft 



(1) Hypothecium thin Phacidiaceae p. 107 



(2) Hypothecium thick Tryblidiaceae p. Ill 



2. Apothecia light-colored, mostly white Stictidaceae p. 109 



B, Algal host-cells present, forming a more or less 



evident thallus Graphidaceae p. 104 



Family 37. HYSTERIACEAE 

 2:721, 9:1100, 11:385, 14:710, 16:657, 17:893, 22:557, 24:1112; Rehm 1 



Apothecia erumpent or superficial as a rule, sometimes innate and concrete 

 with the epidermis, elongate-elliptic, oblong or linear, occasionally extended verti- 

 cally, typically black, carbonous or membranous, opening by a narrow cleft, or this 

 wider and exposing the disk, typically separate, very rarely cespitose or stromate; 

 asci mostly cylindric and 8-spored, paraphyses regularly present, usually much 

 branched at the tip and concrete into an epithecium; spores various. 



The elongate cleft ascoma distinguishes this family readily from the Sphaeriaceae. 

 The rimose opening resembles that of the Lophiostomaceae, but the form of the 

 ascoma and the absence of the thickened ostiole render their separation a simple 

 matter. The fruit-body has usually been called a perithecium or hysterothecium, 

 but the presence of an epithecium justifies the application of the term apothecium, 

 first used by Rehm. This is further warranted by the difficulty experienced in 

 drawing a clear line between this and the three succeeding families, by general 

 consent assigned to the Discomycetes. Genera with hysterioid apothecia appear 



