362 PLANT DISEASES 



flexuous tips, mixed with the mycelium ; asci globose or 

 broadly ovate, 55-68x42-54 ^\ spores up to 8, broadly 

 elliptic, hyaline, 15-20X12-15 /A. 



Sphaerotheca mors-uvae, Berk, and Curt, Grew., iv. 

 p. 158. Mycelium dense, thickish, margin white, centre 

 brownish ; perithecia minute, closely gregarious, black, 

 globoso-depressed, rugose, left prominent by the collapsing 

 mycelium, spores 15 ^ long. 



Erysiphe, Hedw. Perithecia superficial, spherical or 

 hemispherical, submembranaceous, yellow then blackish ; 

 appendages simple or vaguely branched, never dichotomous, 

 intermixed with the mycelium, often undifferentiated or 

 absent ; asci, many in a perithecium ; spores hyaline ; 

 conidia Oidium erysiphoides. 



Erysiphe communis, Fries, Summa Veg. Scand., p. 406. 

 Mycelium effused, arachnoid, persistent, or evanescent, 

 on both surfaces of the leaf; haustoria lobed; perithecia 

 minute, scattered, or gregarious ; appendages short ; asci 

 subglobose, 4-8-spored, 4-8 in a perithecium, no X 72- 

 80 fJL] spores elliptical, 40-42, 20-22 /x. 



Asterula, Sacc. Perithecia seated on blackish, radiating, 

 subsuperficial mycelium, lenticular or globoso-depressed, 

 almost mouthless, membranaceous ; asci generally octo- 

 sporous ; spores continuous, hyaline. 



Asterula beijerinckii, Sacc., SylL> ix. 376 = Ascospora 

 beijerinckii, Vuill., Journ. de Bot., 1888, p. 255 figs. 

 Mycelium plentiful, crustaceous ; perithecia globoso- 

 depressed ; mouth very minute or absent, 100-130 //, diam., 

 black, carbonaceous, erumpent ; asci numerous (up to 40), 

 obovate, then cylindrical, no X 20 /*; spores elliptical, 

 ends obtuse, continuous, hyaline, 17X5-7 p. 



