60 



PLANT STRUCTURES 



large one, and contains a great variety of forms. All of 

 them, however, produce spores in asci, but the asci are not 

 always inclosed by an ascocarp. Here belong the common 

 blue mould (Penicillium), found on bread, fruit, etc., in 

 which stage the branching chains of conidia are very con- 

 spicuous (Fig. 43) ; the truffle-fungi, upon whose subter- 



FIG. 43. Penicillium, a common mould : A, mycelium with numerous branching 

 sporophores bearing conidia; B, apex of a sporophore enlarged, showing branch- 

 ing and chains of conidia. After BREPELD. 



ranean mycelia ascocarps develop which are known as 

 " truffles " ; the black fungi, which form the diseases known 

 as " black knot " of the plum and cherry, the " ergot " of 

 rye (Fig. 44), and many black wart-like growths upon the 

 bark of trees ; other forms causing " witches'-brooms " (ab- 

 normal growths on various trees), " peach curl," etc., the 

 cup-fungi (Figs. 45, 46), and the edible morels (Fig. 47). 



