1909-1910-] Parasitic Moulds and Mildews. 20 1 



from Didymaria Ungeri, which produces withered spots on 

 buttercup-leaves. 



P. obovata Bon. — Frequent on Corn Spurrey, usually 

 causing considerable swelling and distortion of the affected 

 leaves and stems. 



P. trifolioritm De Bary. — Frequent on leaves of various 

 species of Clover and Trefoil, which it coats on the under sur- 

 face with a thinly-spread covering of scattered conidiophores. 



P. grisea (Ung.) De Bary. — Frequent on leaves of Brook- 

 lime. The affected leaves are changed to a pale yellow colour, 

 and bear greyish conidiophores abundantly on their lower 

 surface. This parasite also occurs on various other species 

 of Speedwell. 



P. effusa (Grev.) Eabh. — Frequent on leaves of various 

 species of Chenopodiacese, such as Spinach, Goosefoot, Orache, 

 &c. 



P. urticce (Lib.) De Bary. — Frequent on leaves of the 

 Common and Annual Nettles. This must be carefully dis- 

 tino-uished from Ramularia iirticce, which occurs on the former 

 host-plant. 



P. Candida Fckl. — Not common, but sometimes locally 

 abundant, on leaves of Primrose. It is readily detected by 

 the pale spots which it produces on the leaves, and by the 

 effused patches of white conidiophores, bearing broadly ellip- 

 tical conidia, which are developed on the lower surface of 

 these spots. 



P. alta Fckl. — Apparently common, but liable to be over- 

 looked. It is parasitic on the Great Plantain, where its 

 presence may be detected by the paler colour and more 

 erect habit of the affected leaves. These bear conidiophores 

 scattered thinly over their lower surface. 



P. sordida Berk. — Not common on leaves of common Fig- 

 wort. The affected spots are pale above, and felted below 

 with violet-grey conidiophores. The oospores of this species 

 do not appear to be developed. 



Hyphomycetes. 



The epiphytal moulds and mildews to be mentioned as 

 included in the Hyphomycetes are represented by 4 genera 



