7 6 FUNGI IMPERFECTI 



5. Hyphae spirally twisted. BOSTRICHONEMA. 

 Hyphae not spirally twisted. DIDYMARIA. 



6. Conidia ovate-cylindric. RAMULARIA. 

 Conidia obclavate-pyriform. PIRICULARIA. 

 Conidia vermiform or filiform. CERCOSPORELLA. 



Of the above genera, Botrytis is often seen growing on dying 

 plants in greenhouses, particularly on slips just planted which 

 have been kept ovenvarm and moist ; it also appears to be some- 

 what parasitic (PI. 5. f. 10). Most of the genera are small. 

 Oidiiun is made up mostly of conidial stages of the Erysibaceae. 

 Besides the genera mentioned there are some eighty-five others 

 mostly saprophytic, almost any of which may be found with us, 

 though many have not yet been reported as American. 



The family DEMATIACEAE with fuscous or black floccose hy- 

 phae is a large one ; while the spores are occasionally nearly or 

 quite hyaline the hyphae are always fuscous or dark brown. The 

 genera containing leaf parasites can be distinguished by the fol- 

 lowing synopsis : 



1. Conidia I celled, ovoid or oblong, blackish or sub-hyaline on fuscous 



hyphae. 2. 



Conidia 2-celled, ovoid or oblong. 6. 



Conidia varying from ovoid to vermiform, ^-many-celled by septa at 



right angles to the long axis, fuscous. 8. 



Conidia globose or oblong, muriform (dictyoid). 13. 



2. Hyphae short, scarcely distinct from the globose or ovoid conidia. 3. 

 Hyphae longer, distinct from the conidia. 4. 



3. Conidia solitary. CONIOSPORIUM. 

 Conidia in chains. TORULA. 



4. Conidia fuscous. 5- 

 Conidia hyaline on fuscous hyphae, erumpent, fusoid. ELLISIELLA. 



5. Hyphae creeping, with curved branches. CAMPSOTRICHUM. 

 Ilyphae erect, fasciculate, rather short. HADROTRICHUM. 



6. Hyphae erect, short, somewhat fasciculate. 7. 

 Hyphae erect, short, flexuose (parasitic on clover). PoLYTHRINCIUM. 

 Hyphae more or less spreading, branched ; conidia often in short 



chains (more often saprophytic). CLADOSPORIUM. 



7. Conidia borne only at apex. FUSICLADIUM. 

 Conidia both apical and lateral. SCOLECOTRICHUM. 



