FUNGI IMPERFECTI 289 



(hyalosporic). There are supposedly about three hundred species, all 

 of which are parasitic. Some species are connected with Glomerella 

 or related genera (cf. Glomerella rufomaculans, page 271). 



Colletotrichum, including about forty species, has characters 

 similar to the preceding except that the acervuli are bordered by 

 from few to many dark, rigid setae, usually several times the 

 length of the conidiophores. 



Marssonia is a genus similar in development to Gloeosporium 

 except that it possesses, as a rule, less extensive acervuli, two- 

 celled (hyalodidymic) spores, and it occurs on leaves only. 



Septogloeum is another genus of the Gloeosporium type except 

 that the long-elliptical or cylindrical conidia are pluriseptate. 



Coryneum is characterized by simple conidiophores and dark, 

 triseptate or pluriseptate conidia (phaeophragmic) without append- 

 ages of any kind. The conidia are not set free in horn-like or 

 tendril-like masses. 



Pestalozzia is readily distinguished by the peculiar conidia, 

 which are more or less elliptical, triseptate or pluriseptate, the 

 apical and basal cells being hyaline or very light colored, and the 

 central cells dark. The apical cell is provided with one or more 

 filiform appendages. The conidiophores are also filiform. 



Cylindrosporium is comparable to Septogloeum except that the 

 spores are filiform or needle-shaped, usually curved and continuous. 



III. SPH/EROPSIDALES 



Phoma. In members of this genus the pycnidia are single, or 

 sometimes closely aggregated. They are immersed in the tissues 

 of the host until maturity, when the epidermis is ruptured. The 

 conidia are small, hyaline, usually ovate or elliptical, and continu- 

 ous. The genus is arbitrarily limited to those species having 

 spores less than 1 5 p., larger forms being relegated to Macro- 

 phoma. Species of Phoma inhabit fruits, twigs, or, in some 

 cases, all parts of the hosts, but they are considered to produce 

 no definite spots. About eleven hundred species of this genus 

 are recognized, but relatively few of these have been determined 

 by broad comparison or careful cultural studies. 



Phyllosticta applies to species similar, morphologically, to those 

 in the preceding genus. Phyllosticta, however, produces definite 



