THE FUNGI WHICH CAUSE PLANT DISEASE 



229 



Acanthostigma de Notarjs (p. 226) 



Perithecia free, globose or ovate, very small; walls leathery, 

 black, beset with stiff bristles, ostiole 

 short; asci usually cylindric, rarely 

 ovate, 8-spored ; spores spindle-shaped, 

 multicellular by cross walls, hyaline; 

 paraphyses few or none. 



There are some thirty species, 

 mostly saprophytes. 



A. parasiticum (Hart.) Sacc. '*'"''* 



Perithecia globose, minute, with 

 rigid divergent hairs, 0.1-0.25 mm. 

 in diameter; asci 50 n long, early 

 disappearing; spores fusoid, straight 

 or curved, smoky, 15-20 /x, continuous 

 or 2 to 3-septate. 



Common on leaves of Abies, Tsuga 

 and other conifers in Europe and 

 America. The hyaline mycelium 

 grows on the lower sides of branches 

 and onto the leaves killmg them 

 and matting them to the branches. 

 The mycelial cushions later turn brownish and eventually very 

 small perithecia form on them. 



Fig. 163.— Perithecium of A. Tri- 

 chosphseria parasiticum, show- 

 ing ostiole, bristles, asci, para- 

 physes and spores. After 

 Hartig. 



Herpotrichia Fuckel (p. 226) 



Perithecia superficial, globose or subglobose, texture firm, 

 coriaceous to subcarbonous, hairy or smooth, ostiole papillate 

 or not; asci oblong to clavate; spores fusiform, 2 or many-celled, 

 hyaline or brown; paraphyses none. 



The species, numbering about twenty-five and growing on 

 woody plants, are mostly saprophytes. 



H. nigra Hart.'*^ 



Mycelium dark-brown, widely spreading, haustoria slender, 

 lighter in color; perithecia globose, dark, 0.3 mm. in diameter; 

 asci elongate, 76-100 x 12 /*; spores constricted, 1-3 septate. 



