MILDEWS AND RELATED FIXGI 1 65 



The apogamous formation of fruit also occurs in this suborder. The 

 asci are united into definite, usually flat layers, which are in open 

 fruit bodies known as apothecia. Conidiosj)ores are also found in 

 some of the forms and the conidiophores are of diverse character. 

 The asci are usually eight-spored. The fungi of this suborder are 

 either parasitic, or saprophytic in habit, and a few of the fleshy members 

 of the family Pezizaceje are edible. 



Family i. HYSXERiACEiE. — ^The apothecium is elongated and the 

 opening is a long wide deft between the approaching walls of the 

 apwthecium. so that the asdgeral layer is exposed at the time of the 

 spore discharge. 



Some species of the genera Lophodarmium and Eypoierma are 

 dangerous parasite of leaves; for example, L. pinastri attacks pine 

 leaves; L. neroisequum attacks the spruce tree; while Hypodermn 

 brackysporum is found on the white pine, Pinus strobus. Such genera 

 as Lopkium, Hysterium, and Gloniitm include species which are sapro- 

 ph^-tic on bark and wood. 



Fatltttv 2. PHACn>i.ACE£. — ^The apothecium is rounded, seldom 

 elongated and its walls are separated through a star-shaped opening, 

 rarely a deft-like opening, so that the ascigeral layer is fully open at 

 maturity. The family indudes such paradtes as yemacydtis nitxus 

 on coniferous needles; Skytisma acerinum. which produces black tar- 

 like blotches on maple leaves; and R. saJicinuni. which causes similar 

 black areas on willow leaves. Several spedes of TrockUa are found 

 on the leaves of different plants. 



F.AMTLY 3. Pyrohem-ACEj:. — ^The fruit body is placed on fine 

 hyphae or on a felt-like cushion of hyphae. At first it is spheric; later, 

 it is flatly expanded. The h>'pothedum is occasionally feebly de- 

 veloped, at other times it is strongly so. The peridium is poorly formed, 

 or entirely absent. The most interesting genus is Pyronema. P. 

 amfiuens has a fruit body i mm. acr(Bs, and of a yellow or reddish 

 color. It is often found in spots where fires have been kindled in the 

 woods. The structiu^ of the apothedum and the method of its forma- 

 tion following the sexuad imion of an antheridium and oogonium have 

 been described by Harper' and the essential details have been given 

 on a former page of this book {ante, pages 12^ and 126). 



1 Hakper, R. a. . Sexual Rqtroduction in Pyromema confiuens and the Mor- 

 phology of the Ascocaip. Annals of Botany, 14: 231-400, 1900 



