PHOMA. 4()9 



Ph. malvacearum West. On mallows and hollyhock in Europe. 



Ph. longissima (Pers.). In species of Umbeliiferae and ChenojKxliaceae 

 ill Euidpe and America. 



Ph. errabunda Desni. In stems of Vcrbasciim. (Britain.) 



Ph. cucurbitacearum (Fr.). On fruits of various species of Cucur- 

 bitaceae in Euidpc and America. 



Dendrophoma. 



Pycnidia similar to Phorim, coniciiophores however bearing 

 several conidia either on lirancbes or little processes 



Dendrophoma Marconii Cav. attacks Hemp {Cannabis sativa), 

 causing dark (jblong spots on the green stem. The pycnidia 

 are embedded and l»reak tbrougb the epidermis with a idiind 

 pore. The conidiophores are branched, with swollen ends 

 carrying little short rod-like unicellular conidia. In case of 

 attack, which generally occurs towards the close of the 

 vegetative period of the hemp, it is suggested to cut the 

 crop somewhat prematurely, and thereby prevent maturing and 

 spreading of the fungus. 



D. convallariae Cav. produces dark elont;ated sjjots on leaves of Con- 

 vallaria iii'ijulu. 



D. valsispora Penz. is recorded by Penzig on liviiij: leaves of CiMis 

 Limoioiiu (Lemon). 



Sphaeronaema. 



Pycnidia embedded, niemliranous, and long-beaked. Conidia 

 ovoid or olilong, unicellular, and almost colourless. 



Sphaeronaema fimbriatum (Kll. et Hals.), {Crraton/stis 

 fimhriafd Ell. et Hals.). Jilack rot or black shank of sweet 

 potato.' The parasite shows itself as black depressed spots on 

 the lower parts of young plants, and these may extend over 

 the whole shoot. The di.sease is best recognized on the tubers, 

 where it consists of dark, somewhat greenish spots, varying 

 from \ to 4 inches in diameter, and extending some distance 

 into the tissue. These spots when once seen cannot be mis- 

 taken, as they are sunk areas with distinct margins, like spots 

 burned into the potato with a piece of metal wliich has left 

 the skin uninjured. The mycelium consists of thick-walled 

 olive-brown hypliae, which cau.se death and destruction to the 



iHalsted and Faiichild. Jour, of Myrolo,,y, V..1. vii.. IMIM. witli Figures. 



