THE FUNGI WHICH CAUSE PLANT DISEASE 481 



Conidia unappcndaged 

 Pycnidia free in the substratum; sub- 

 iculum none 

 Pycnidia not beaked, opening by a 

 pore, or irregularly 

 Not growing on other fungi 

 Pycnidia opening by a regular pore 

 Pycnidia more or less sunken in the 

 substratum 

 Pycnidia globose, etc. not spindle- 

 shaped 

 Pycnidia borne on dark colored 

 spots, or on wood, globose 

 Conidiophores simple or nearly 

 so 

 Pycnidia rather large 

 Pycnidia at first covered, 



then erumpent 

 Spores xmder 15 M 



On leaves only 1. Phyllosticta, p. 483. 



Not on leaves 2. Phoma, p. 490. 



Spores over 15 m 3. Macrophoma, p. 493. 



Pycnidia from the first super- 

 ficial 4. Aposphseria, p. 494. 



Pycnidia very small, closely 

 aggregated on dark spots 



on the leaf 5. Asterostomella. 



Conidiophores branched 6. Dendrophoma, p. 494. 



Pycnidia scattered, superficial, 

 circular, conidia elongate or 



cylindric 7. Crocicreas. 



Pycnidia globose; conidiophores 



circinate 8. Pyrenotrichum. 



Pycnidia horizontal, free, cylin- 

 dric 9. Glutiniuin. 



Pycnidia opening irregularly, or 

 operculate 



Spores globose 10. Mycogala. 



Spores elongate or ellipsoid 



Pycnidia operculate 11. Piptostomum. 



Pycnidia opening irregularly 



