PERISPORIEAE. 18] 



Species of fungi included in this group are the cause of 

 those black, sooty coatings found on leaves frequented by green 

 fly (Aphis) and other leaf-insects. These are purely epiphytic 

 and saprophytic forms which derive nourishment from the 

 "honey-dew" excreted by the insects.-^ They multiply very 

 rapidly, and soon form dark coatings on the upper side of 

 leaves and twigs. Little damage need be feared, since the 

 leaves retain their green colour, and the coating is not enough 

 to stop access of light. Amongst them are species of Cap- 

 nodium, Meliola, and Apiospormm, as well as the conidial forms 

 Fumago, Torula, Antennaria. 



The modes of reproduction of these forms are exceedingly 

 varied. According to Zopf^ they form: (1) ascocarps; (2) many- 

 celled large conidia ; (3) unicellular, very small conidia ; (4) 

 isolated and clustered conidiophores ; (5) gemmae; (6) buds in 

 a yeast-like manner ; while every fragment of a mycelium can 

 produce a new growth. Any of the species may frequent 

 many various plants, and can pass easily from one host to 

 another. Some of the better-known forms are : 



Capnodium salicinum Mont. (Britain). This occurs on 

 species of willow, poplar, hop, and many other plants. 



If it appears early and abundant on hop it may cause 

 considerable damage. {Fumago vagaiis is a conidial form). 



C. quercinium Pers. on oak. (U.S. America.) 



C. taxi Sacc. et Eoum. on Taxus. 



C. foedum Sacc. (spermogonium form = Chaetophom.a foeda). 

 On the leaves of oleander. (U.S. America.) 



The genus Apiospoiium forms similar sooty coatings. 



A. pinophilum Fuck. This covers with a black coating 

 whole twigs and leaves of silver fir ; the needles however retain 

 their green colour completely. (Antennaria and Torula are 

 forms of this.) 



A. rhododendri Fuck. ; A. ulmi Fuck. ; and other species. 



The conidial form Pellicularia which produces grey coatings on the coffee- 

 plant is considered among the Hyphomycetes. 



Species of Meliola also produce sooty coatings. 



M. citri Sacc. and M. Penzigi Sacc. occur on Citrus in 



' Biisgeii, Der Honigthau. Siologische Stndien an PJlanzen. Jena (Fischer). 

 -Zopf, "Die Conidienfriiohte v. Fumago.'' Nova acta, Bd. 40. Also: Zopf, 

 Die Pike ; Tulasne, Select, fung. , iii. 



