506 FUNGI IMPERFECTI. 



2. Sect. Didymosporae. 



1. Suhsect. Micronemeae. 



Dicoccum. 



Conidia oblong, two-celled, and arising from short simple 

 conidiophores. Mycelium subcuticular. 



Dicoccum (Marsonia) rosae (Bon.) causes brown spots on 

 living leaves of roses, and a premature leaf-cast takes place. 

 Little mycelial stromata develop between the epidermal cells 

 and their cuticle, and give off two-celled hyaline conidia. 



D. iiniseptatum B. et Br. forms dark patches on twigs of 

 Clematis vitalba. (Britain.) 



D. lathyrinum Ell. et Gall. On living leaves of Lafhyrus 

 ochroleucus in America. 



Cycloconium. 



Mycelium subcuticular. Conidia one- to three-celled. 



Cycloconium oleaginum Cast.^ When this fungus is present, 

 the leaves of the olive show roundish light-brown spots with 

 dark margins, then becoming discoloured, they roU up and drop 

 off. The mycelium grows in the walls of the epidermal cells, 

 branching dichotomously ; branches of the hyphae break out 

 through the cuticle as sac-like cells, which become the conidio- 

 phores. The conidia consist of one to three cells. Kruch 

 states that Cercospora cladosporioides is often present along with 

 this disease of the olive, and may take some part in causing it. 



Peglion states that this or an allied species occurs on leaves 

 of Quercus Hex. 



2. Suhsect. Macronemeae. 



Passalora. 



Conidia oblong or spindle-shaped, two-celled, and borne on the 

 apex of greenish pluriseptate conidiophores, arising from an 

 olive-green mycelium. 



Passalora bacilligera M. et Fr. occurs on living leaves of 

 Alnus glutinosa. (Britain.) 



P. microsperma Fuck. This frequently covers the whole 

 lower surface of the leaves of Alnvs incana with little tufts of 



'Kruch, BiUletin soc. hot. itod., 1892. 

 Boyer, Becherches sur les maladies de VOlivier, Montpellior, 1892. 



