PHACIDIALES 



53 



The remaining two families, Hypodermataceae with nine genera 

 and the Hysteriaceae, best known of all, with fourteen genera 

 contain the majority of the species from America and elsewhere. 



LITERATURE. 



Saccardo. Sylloge Fungorum, 2: 721-813; 9: 1094-1129; 

 ii : 385-390. 



Rehm. Rabenhorst's Kryptogamen Flora Deutschlands, u. s. 

 w. i 3 : 1-56. 



Ellis & Everhart. North American Pyrenomycetes, 673-727. 

 1892. 



Duby. Memoire sur la Tribu des Hysterinees. Mem. Soc. 

 Phys. et d'Hist. Nat. Geneve, 16 : 15-70. //. /, 2. 1861. 



Lindau. Die natiirlichen Pflanzenfamilien ii : 265-278. 



Order 12. PHACIDIALES. 



The Phacidiales are partly saprophytic and partly parasitic 

 plants in which the ascoma is usually roundish or stellate and 

 remains enclosed for a long time in a tough covering which be- 

 comes torn at maturity of the spores. The order is composed of 

 three families which may be distinguished as follows : 



1. Ascocarps soft, fleshy, bright-colored ; disc mostly bright-colored, sur- 



rounded by the lobes of the ascocarp (saprophytic) Stictidaceae. 

 Ascocarp leathery or carbonaceous, always black. 2. 



2. Ascocarps at first sunken, later strongly erumpent, hypothecium thick 



( saprophytic ) . Tryblidiaceae . 



Ascocarps remaining sunken in the substratum ; hypothecium thin, 



poorly developed (parasitic or saprophytic). Phacidiaceae. 



All the above families are of considerable size, the Stictidaceae 

 having twenty-two genera, the Triblidiaceae six, and the Pha- 

 cidiaceae seventeen. Among the parasitic members of the last 

 named family, Rhytisuia is one of the most familiar genera, spe- 

 cies occurring on the leaves of maple, holly, willow and andro- 

 meda, forming raised black blotches ; one of the two species on 

 maple leaves is often abundant and conspicuous. A species of 

 Phacidium causes the brown spots frequently seen on the leaves 

 of sweet clover. Trochila also contains some leaf-inhabiting 

 parasites. 



