SPHA ER OPS ID A LES 



69 



others from the known world. Nearly four hundred and fifty 

 named genera are included in the three orders. 



Order i. SPHAEROPSIDALES. 



Among the fungi imperfect! the Sphaeropsidales are so named 

 because of the fact that they produce structures resembling the 

 perithecia produced by the Sphaeriales. These perithecia like 

 bodies are the pycnidia (P/. j, f. 2], and the spores instead of 

 developing in asci are produced from the walls of the pycnidium 

 direct. The group is a very extensive one including a number of 

 leaf-spot diseases of cultivated plants. Among these are those of 

 the apple, catalpa, maple, celery, sweet potato and violet caused 

 by species of Phyllosticta ; those of currants, raspberries, carna- 

 tions, horseradish and lettuce caused by species of Scptoria ; that 

 of the rose caused by Actinonema, and a number of others. 

 While the greater number of the species are saprophytic on stems, 

 branches, etc., there are extensive genera of parasitic forms. 

 Among these are Phyllosticta with over 400 species and Scptoria 

 with over 600 species, a fair proportion of which are found in 

 America. In most of the species the pycnidia are black, but in 

 the small family Zythiaceae they are light colored. 



The four families can be distinguished as follows : 



1. Pycnidia globose, conic or lenticular. 2. 

 Pycnidia more or less dimidiate, irregular or shield-shaped, black. 



Leptostromataceae. 

 Pycnidia cup-shaped or patelliform, black. Excipulaceae. 



2. Membranous, carbonaceous or coriaceous, black. Sphaeropsidaceae. 

 Fleshy or waxy, light colored. Zythiaceae. 



Among the SPHAEROPSIDACEAE the larger genera with simple 

 hyaline spores are Phoma and Vermiciilaria which are sapro- 

 phytic, and Phyllosticta parasitic on leaves. Ampelomyces is a 

 minute form parasitic on the hyphae of various Erysibaceae.* 

 (PI. S-f- J-) Sphaeropsis has simple brown spores and Diplodia 

 has two-celled brown spores. 



Among the genera with hyaline two-celled spores are Ascochyta 

 and Actinonema, one of the species of the latter forming black 



* Cf. Griffiths. The common Parasite of the Powdery Mildews. Bull. 

 Torrey Bot. Club, 26 : 184-188. //. jjS. 1899. 



