478 



CLASS BASIDIOMYCETEAE 



await further studies in an attempt to determine whether the structural 

 differences within the group show definite correlations with the stichic 

 or chiastic position of the nuclear spindle in the meiotic divisions of the 

 diploid nucleus of the basidium. 



Pistillaria is a small fungus usually not over 2 to 5 mm. tall, with no 

 sharp distinction between stalk and hymenium-bearing portion, which 

 is clavate. No sclerotium is present. Some of the species have two-spored 

 basidia, others have four spores to each basidium. Growing on soil or 

 dead stems, leaves, etc. Also small, but much taller than the foregoing, 

 is the genus Typhula whose spore fruits grow from sclerotia and form 

 very slender filiform stalks, sometimes branched, with the terminal por- 

 tions thickened to form spindle-formed hymenophores. A number of 

 species are parasitic upon grasses, sugar beets, potatoes, etc. Miss 

 Remsberg (1940) studied the two genera and determined the presence 

 and absence of sclerotia to be the best distinguishing character. 



Physalacria is also small, up to 2 cm. tall, consisting of a slender stalk 

 and a downturned, hollow, fleshy head on whose lower surface the 

 hymenium is most abundantly developed. For this reason McGuire (1939) 

 suggested that the genus should be placed in the Thelephoraceae as was 



Fig. 156. Polyporales, Family Clavariaceae. Clavarindelphus pistillaris (Fr.) Donk. 

 (Courtesy, Coker: The Clavarias of the United States and Canada, Chapel Hill, Univ. 

 is'^orth Carolina Press.) 



