114 



GRASSES OF IOWA. 



Fig. 63. Common Herbarium mould. (1) general appearance, showing long conldl- 

 ophore and sterlgmati on end; (2) perltheclum with one of Its ascl and ascospores; (3) 

 contents from an unripe perlthecium; (4) a small part of a mycelium with conldlophore 

 c, and spore bearing sterigmata, young ascogonlum a. s. (DeBary except J.) 



mycelium enters the kernel because of the dissolving action 

 of an enzyme produced by the mycelium. From this my- 

 celium erect threads (conidiophores) arise. These are en- 

 larged at the end. Prom the enlarged portion of the 

 conidiophores numerous small and radia ing stalks (sterig- 

 mata) are produced, each bearing a chain of spores, the 

 end spore of the chain being the older. These spores 

 germinate under favorable conditions of moisture and 

 heat, and again give rise to the same stage. In addition to 

 this, the condidial stage, a second kind of reproductive body 

 occurs. This is produced by the coiling of a branch of the 

 mycelium having several turns. Two or three slender branch- 

 lets grow from the base. One of these grows more rapidly and 

 connects with the tc p of the spiral coil formed first. The 

 contents of those last formed unite with the spiral known as 

 theascogonium. After fertilization a perithecium is produced. 



