ORDER ERYSIPHALES (PERISPORIALES OF MOST AUTHORS) 319 



tive hyphae grow to produce a dark-colored, shield-like stroma. From the 

 stalk cells of the oogone and antherid hyphae grow out and form a 

 perithecium around these organs, under the stromatic shield. The 

 fertilized oogone elongates and divides into a number of uninucleate cells 

 of which two or three near the apex send out several branched ascogenous 

 hyphae which produce typical hooks which give rise to the asci. A few 

 paraphyses appear among the asci while from the upper part of the peri- 

 thecium arise periphyses which grow up together and pierce the stromatic 

 shield and spread apart to produce the ostiole. The eight nuclei produced 

 in each ascus in the usual manner are taken up by two's into the four- 

 developing ascospores. Two of these binucleate ascospores are destroyed 

 by the growth of the other two which eventually become five-celled, with 

 one nucleus in each cell except the middle cell which is binucleate. The 

 presence of a true ostiole lined by periphyses and the occurrence of 

 paraphyses would seem to suggest that perhaps this genus is more closely 

 related to the Sphaeriales. 



In this family Theissen and Sydow (1917) distinguish 19 genera of 

 which Meliola and Irene with many hundreds of species each are very 

 abundant in the tropics. A few species occur even in temperate regions. 

 Stevens (1927, 1928) wrote a monograph of the genus Meliola which is 

 indispensable for the recognition of the species of this difficult genus. He 

 differs considerably from Theissen and Sydow in his interpretation of the 

 relationships of the genera centered about Meliola. In a subfamily 

 Meliolineae he includes Adinodothis, placed by those authors in Family 

 Polystomellaceae of the Hemisphaeriales, and Amazonia, assigned by 

 them to Family Microthyriaceae, of the same order. Both of these genera 

 have the same type of asci and ascospores. The perithecia of Amazonia 

 have been found to be complete, not incomplete below, and the spreading 

 mycelium has hyphopodia like those of Meliola and Irene. (Fig. 102 B.) 



The fact that some genera of Family Capnodiaceae have much this 

 same type of superficial mycelium, with hyphopodia or bristles would also 

 indicate that the classification of the Meliolaceae and Capnodiaceae, as 

 well as of the Englerulaceae (see below) is rather artificial. Arnaud's 

 studies in this field (1925) suggest lines for a better arrangement when 

 more extensive investigations can be completed. 



Family Englerulaceae. These are leaf parasites whose perithecial 

 cells dissolve into slime at maturity, exposing the enclosed asci. The 13 to 

 15 genera and 20 to 30 species are with few exceptions tropical. Petrak 

 (1928) after an extensive study o.'' most of the genera assigned by Theissen 

 to this family decided that it is a collection of heterogeneous forms placed 

 together on account of the one common character, the slimy dissolution 

 of the perithecia. Since this characteristic is known in other orders, e.g., 

 Hemisphaeriales in some genera of Microthyriaceae and of Polystomel- 



