FUNGI IMPERFECTI 287 



Botrytis. This genus, although somewhat indefinitely character- 

 ized, differs from the preceding chiefly in having spores grouped 

 at the tips of branches and ordinarily borne on papillae or tooth- 

 like projections. 



Cephalothecium is characterized by relatively long, unbranched, 

 upright conidiophores, at the tip of each of which may be produced 

 a cluster of two-celled, hyaline (hyalodidymic), usually pear-shaped 

 conidia. 



Ramularia. The mycelium is wholly within the tissues of the 

 host, the conidiophores are hyaline, straight or flexuous, single or 

 fascicled. The conidia are single or loosely adherent in chains. 

 They are narrowly elliptical to cylindrical, and divided into three 

 or more cells (hyalophragmic). 



Cercosporella. This genus is related to the preceding on 

 account of its hyaline conidiophores and conidia, but on the 

 other hand it is very close to Cercospora, subsequently described, 

 on account of the filiform spores (scolecosporic) and sometimes 

 geniculate conidiophores. 



Piricularia differs from the preceding genus in having conidia 

 which are strongly obclavate to pyriform and generally pluriseptate. 



2 . (Dematieae ; mycelium dark, at least with age ; spores 

 generally dark.) 



Fusicladium. The mycelium produces short conddiophores 

 which may be single or in small clusters. These produce at 

 the tips elliptical conidia which at maturity are two-celled and 

 colored (phaeodidymic) (cf. Venturia, page 264). 



Polythrincium differs from the last-mentioned genus chiefly in 

 the nodulose or twisted conidiophores. 



Scolecotrichum. These forms possess, instead of nodulose 

 conidiophores, those which are geniculate, a knee being formed 

 as the conidiophore is prolonged by growth on one side of each 

 spore successively produced. The spores are more or less ellip- 

 tical and two-celled. 



Cladosporium. In this genus there is less regularity in the 

 form of the conidiophores and the sizes of spores, as the conidio- 

 phores are considerably branched, and these branches may be- 

 come spores. The conidiophores are olivaceous, also the ovate, 

 eventually two-celled conidia. 



