154 THE FUNGI WHICH CAUSE PLANT DISEASE 



nature of the fungus is in doubt." The entire height of the as- 

 cocarp is 2 mm.; head white, then grayish brown; asci cylindric, 

 8-spored; spore tinged with brown, 4-5 fi in diameter. The species 

 as a pathogen is usually referred to as Roesleria hypogaea Thiim 

 & Pass, and given a place in the Geoglossacese; but Durand ^^ fol- 

 lows Schroter in excluding the species from that family. Fig. 109. 



Phacidiales (p. 124) 



This order, comprising some six himdred species only a few of 

 which are pathogens, is characterized as follows: mycelium well 

 developed, much branched, multiseptate; ascocarps fleshy or 

 leathery, free or sunken in the substratum or in a stroma, 

 rounded or stellate, for a long time enclosed in a tough cover- 

 ing which at maturity becomes torn; paraphyses usually longer 

 than the asci, much branched, forming an epithecium. 



Key to Families of Phacidiales 



Ascocarps soft, fleshy, bright colored 1. Stictidacese, p. 154. 



Ascocarps leathery or carbonous, always 

 black 

 Ascocarps at first sunken, later strongly 



erumpent, hyjwthecium thick 2. Tryblidiaces, p. 155. 



Ascocarps remaining sunken in the sub- 

 stratum, hypotheeium thin, poorly 

 developed 3. Phacidiaceae, p. 155. 



Stictidaceae 



The members of this family (about twenty genera and two 

 hundred fifty species) are usually considered saprophytes, al- 

 though one species of Stictis has recently been described as a 

 parasite. 



Stictis Persoon 



Perithecia sunken, pilose, at length erumpent; asci cylindric, 

 containing eight filiform, multiseptate spores; paraphyses filiform] 



