PHYSARUM 77 



mass black; spores by transmitted light violet-brown, distinctly warted, 

 about 10 ix. Plasmodium white, often with blue, green or yellow tints. 



The snow-white, nearly smooth stem and the small sporangium 

 covered with loose calcareous granules distinguish this rare species. 

 It develops on leaves and looks like a small Didymium squamulosum. 



Rare. Maine, Ohio, Michigan, Wisconsin, Iowa, Oregon, Colombia; 

 Europe, South Africa, Java. 



53. Physarum leucopjleum Fr. 



Symb. Gast. 24. 1818. 

 PL V, Figs. 98, 99. 



1797. Trichia filamentosa Trentep., in Roth, Cat. Bot. 1 : 227. 



1817. Physarum conglobatum Ditm., in Sturm, Deutsch. Fl. Pilze 3 : 81. 



1836. Diderma terrestre Fr. ex Weinm., Hymeno-Gastero-Myc. 574. 



1882. Physarum granulatum Balf. fil., Grev. 10 : 115. 



1884. Physarum imitans Racib., Rozpr. Mat.-Przyr. Akad. Krak. 12 : 73. 



1892. Physarum readeri Massee, Mon. 282. 



1893. Tilmadoche nephroidea Cel. fil., Myx. Bohm. 69. 



1894. Physarum nutans Pers. var. leucophaum (Fr.) Lister, Mycetozoa 51. 



Sporangia scattered or gregarious, stipitate; peridium globose or 

 subdepressed, occasionally short-cylindric, 0.5-1 mm. in diameter; 

 plano-convex, but never umbilicate below, erect, bluish ashen; stipe 

 short, rugose, subsulcate, fuscous, brown, or sometimes almost white, 

 even or slightly attenuate upward from a thickened base or some- 

 times from an indistinct hypothallus; capillitium dense, intricate; the 

 nodules white, with comparatively little lime, thin, expanded, angular 

 or branching; columella none; spore-mass black, spores dark violaceous, 

 minutely roughened, about 9-11 fx. 



This extremely delicate and beautiful form is certainly not to be 

 referred to Tilmadoche alba (Bull.). Fries, who seems to have known of 

 P. compressum A. & S., and refers it to P. nutans Pers., annotates 

 the present species: "Species especially remarkable in the stipe, in 

 the internal structure, and in its whole habit, nor is there any other 

 with which it may be compared. . . . Peridium thin, . . . not uni- 

 form, . . . presently breaking up into laciniate scales; at first yellow, 

 then bluish-ashen; when empty, white. The form inconstant, globose, 

 depressed, but never umbilicate at the base." If we may judge by 

 what Fries says on the subject, he certainly distinguished clearly be- 

 tween this species and T. alba (Bull.), to say nothing of the stouter, 

 larger, in every way coarser forms called by Rostafinski P. nefroideum, 

 P. compressum and P. lividum. 



This shadowy little species has had an eventful history, dipping in 



