46 Mycetozoa of North America 



Illustration: Lister, Mycetozoa ed. 3. pi. 199, figs. a-c. 

 Distinguished from P. viride by the rigid capillitium, and 

 somewhat larger, darker spores. 



19. Physarum polycephalum Schw. Schr. Naturforsch. Ges. Leip- 

 zig 1:63. 1822. 



Plasmodium yellow. Total height 1.5 to 2 mm. Sporangia 

 much compressed, lenticular, undulate or lobed, singly or in clus- 

 ters of many sporangia on one stalk, gray or yellow, stalked; 

 sporangial wall membranous, with scattered thin, innate clusters 

 of white or yellow lime-granules. Stalks subulate, slender, in- 

 clined or flcxuose, usually fasciculate of several combined, yellow 

 or tawny, translucent. Capillitium a loose network of slender 

 threads with many flat expansions at the axils; lime-knots yellow 

 or white, variable in shape, size, and abundance. Spores violet- 

 brown, minutely spinulose, 8-11 /x diam. (Plate 7, fig. 3.) 



Type locality: Wilkes County, North Carolina. 



Habitat: On dead wood and leaves; common and abundant. 



Distribution: Throughout North America. 



Illustration: Lister, Mycetozoa ed. 3. pi. 34. 



This species forms large plasmodia, spreading over a wide area, 

 and often, after emergence, feeding on the oyster mushroom 

 {Pleurotus ostreatus) and similar fungi. It is often associated with 

 P. gyrosum, to which it is related, or in the company of PhysareUa 

 oblonga. Var. obrusseum (Berk. & Curt.) Lister is hardly worthy 

 of recognition, as single sporangia are seen in almost every de- 

 velopment, although small colonies of single sporangia do occur. 

 The usual phase is in the form of several sporangia on one stalk, 

 or the sporangia on many stalks and united to form masses 

 comprising up to 30 or more sporangia. 



20. Physarum flavicomum Berk. London Jour. Bot. 4: 66. 1845. 



Plasmodium yellowish green (Lister). Total height 1 to 2 

 mm. Sporangia subglobose, flattened beneath and sometimes 

 above, nodding, about 0.5 mm. diam., yellow, gray, bronze, or 

 dark and iridescent from the absence of lime, stalked; sporangial 

 wall membranous, colorless above, yellowish below, stouter and 

 persistent at the base. Stalk slender, subulate, twisted, without 

 lime, red, copper-colored, or pale brown. Capillitium a close 

 n'et^brkof hyaline threads, with numerous yellow, fiat expansions 



•^^,^.-ft 



