470 FUNGI IMPERFECTI. 



cells of attacked tissues. There are three modes of spore pro- 

 duction : (1) brown macro-conidia inside the tissues; (2) colour- 

 less micro-conidia on the spots ; (3) spherical pycnidia with long 

 necks ending in a fringed opening. A sclerotial form is also 

 strongly suspected. Remedial measures recommended are, de- 

 struction of all diseased parts, change of crop on diseased fields, 

 and selection of healthy seed and strong sprouts. 



Several other species of this genus are recorded from North 

 America, but details in regard to their mode of life are 



wanting. 



Asteroma. 



Fungi forming star-like, dark-grey, rnycelial patches on the 

 surface of plants. Pycnidia very small and containing tiny 

 ovoid or short cylindrical spores. Several species frequent 

 living leaves. 1 



Asteroma impressum Fuck. On Tussilacjo farfara. 

 A. prunellae Purt. On leaves of Prunella vulgaris. (Britain.) 

 A. ulmi Klotsch. (Britain), and A. maculare End. On Ulnm*. 

 A. padi (D.C.) causes a leaf-fall on Prumis Padus. (Britain.) 

 A. geographicum Desru. is found on the leaves of species of Crataegus. 

 Prunus, and Pyrus in Europe and America. 



Pyrenochaeta. 



Pycnidia emergent or sessile, beset with bristles. Conidia 

 oblong, on branched conidiophores. 



Pyrenochaeta rubi-idaei Cav. forms black spots on leaves 

 of Ruhus Idaeus. The pycnidia are spherical with a tuft of 

 bristles projecting from their terminal pore. The conidia are 

 little, oval, and with one or two cells : they are produced from 

 slightly branched conidiophores. 



Vermicularia. 



Conidia unicellular, rarely bicellular, generally spindle-shaped ; 

 they are produced inside pycnidia, and are embedded amongst 

 brown septate hairs. The species are a frequent cause of leaf- 

 spot, but most of them have not yet been sufficiently investigated. 



1 Cicinobiifus Cexafii De Bary, allied to this genius, is a parasite on Oltlium 

 Tuckeri, the dreaded vine-parasite. 



