240 



FORMS OF THE BLACK FUNGI 



ascocarps breaks through the bark of a large variety of trees 

 and shrubs in the form of spherical or cake-like masses (Fig. 

 148). Among the more serious pests may be mentioned the very 

 destructive black rot of grapes, apple and pear scab; bitter rot 

 of apples; the s3xamore blight, and the chestnut bark disease. 



^U 



^. 



Fig. 149. 



A 



Fig. 150. 



Fig. 148. A common black fungus, Hypoxylon: A, habit of the fungus 

 as it appears on dead branches and logs. The round black bodies are an 

 association of the mycelium, stroma, and numerous ascocarps. B, a single 

 ascus enlarged, showing character of the ascospores. 



Fig. 149. The black knot. Plowrightia, infecting a branch of cherry. At 

 the bottom of the branch is shown the early summer or spore-bearing stage, 

 c, and above a black warty mass of ascocarps, as, produced the previous 

 season. 



Fig. 150. A, several ascocarps enlarged, taken from region, as, in Fig. 

 149, B, diagram of an ascocarp as seen in section, showing the asci and the 

 opening for the escape of the ascospores. 



This and the following order represent possibly the consumma- 

 tion of those tendencies that we saw appearing in the third line 

 of departure from the Pezizales. As stated they are characterized 

 by their closed ascocarps. 



90. Order e. Aspergillales or Blue-green and Brown Fungi. — 

 The Aspergillales includes perhaps the most widely distributed 

 and familiar examples of the fungi. They occur as blue-green or 

 brown moulds upon almost any organic matter, forming a deli- 

 cate mycelium from which are developed numerous erect hyphae. 



