SOIL FUNGI 257 



(b) Conidia in chains, Stysanus. Found in the soil 



by Koning, Goddard and others. 



4. Mycelium consists of branched, septated hyphae, growing in 



or on the medium; characteristic fructification; growth 



mostly of a waxy or slimy constituency, often quite tough, 



Tuberculariaceae Ehrenberg. 



(a) Conidia and hyphae hyaline and light colored; sickle 



shaped conidia, both ends more or less pointed, Fu- 



sarium (No. 101, PI. XIV). 

 One of the most common groups of soil fungi; very active in 

 cellulose decomposition. 63 Various species of Fusarium were 

 isolated from soils of different parts of the world. 



(b) Conidia or hyphae dark or gray; conidiophorcs very 



short, conidia netted or prickly, Epicoccum. Rarely 

 found in the soil. 

 II. Melanconiales, Melanconium u is rarely found in the soil. 



III. Sphaeropsidales: 



1. Chaetomella. Found in the soil by Koning and Pratt. 



2. Sphaeronema. Rarely found in the soil. 



IV. Sterile mycelium: 



1. Sclerotia formed: 



(a) Sclerotia abundant, mycelium occupies secondary place, 



Sclerotium. Frequently found in the soil. 



(b) Sclerotia seldom formed, Rhizoclonia. Various Rhizoc- 



tonia, especially Rh. solani, are frequently found in 

 the soil. 



2. No sclerotia formed; hyphae united in strands, Ozonium. 



Often found in the soil (Dale). 

 D. Basidiomycetes, characterized by the formation of a basidium, produc- 

 ing four sterigmata, each bearing a single spore. Among the various 

 subgroups it is sufficient to mention the 



I. USTILAGINALES 



II. Uredinales 

 III. Hymenomycetes and other groups of mushroom fungi. These 

 include various organisms (Mcrulius, Boletus, Russula, etc.) 

 which form mycorrhiza with higher plants 65 and other forms, like 

 Psilocybe, which may become agents in the decomposition of 

 organic matter in the soil. 66 



63 Sherbakoff, 1915 (p. 238); Pratt, O. A. Soil fungi in relation to diseases of 

 the Irish potato in Southern Idaho. Jour. Agr. Res., 13: 73-99. 1918; Taylor, 

 1917 (p. 259). 



64 Edgerton, C. W. The Melanconiales. Jour. Amer. Microscop. Soc, 31: 

 No. 4. 1912. 



65 Peyronel, B. Nuovi casi di rapporti micorizici tra Basidiomiceti e Fanero- 

 game arboree. Bull. Soc. Bot. Ital., No. 1, p. 3-10. 1922. 



66 Thorn, C, and Lathrop, E. C. Psilocybe as a fermenting agent in organic 

 debris. Jour. Agr. Res., 30: 625-628. 1925. 



