Physarum 33 



■ Sporangia flattened, speckled with brown, red, 

 yellow, or white; lime-knots large, angular, 

 pale yellow. 56. P. auriscalpium 



Sporangia subglobose, brown, speckled with 

 paler spots; lime-knots small, angular, yel- 

 lowish or brownish. 57. P. Braunianum 



Sporangia red; lime-knots rounded, yellow, 



often with red centers. 58. P. lateritium 



Sporangia bright yellow, subglobose, not 



heaped; lime-knots small, angular, yellow. 59. P. luteolum 



Sporangia heaped in small clusters, greenish 



yellow; lime-knots irregular, yellow. 60. P. virescens 



Sporangia clustered, not heaped, light brown or 

 tawny; spores small with scattered clusters of 

 warts. 61. P. digUatum 



Sporangia large, yellow, with an outer crust of 

 yellow lime easily separating in flakes from 

 the inner wall. 62. P. alpinum 



1. Physarum leucopus Link, Ges. Nat. Fr. Berl. Mag. 3: 27. 

 1809. 



Plasmodium opaque white or yellowish (Lister). Sporangia 

 gregarious, stalked, globose, about 0.5 mm. diam., grayish white; 

 sporangial wall membranous, containing scattered or clustered 

 lime-granules. Stalk white, stout, tapering upward, erect, brittle 

 with enclosed lime-granules, rising from a more or less developed 

 white, circular hypothallus. Columella none. Capillitium of 

 delicate, branching, hyaline threads connecting large, irregular 

 lime-knots filled with large, white lime-granules. Spores violet- 

 brown, minutely spinulose, 7-10 n diam. 



Type locality: Europe. 



Habitat: On dead leaves, occasionally on dead wood; not 

 uncommon. 



Distribution: Widely distributed throughout the United 

 States and Canada; *Canal Zone. 



Illustration: Lister, Mycetozoa ed. 3. pi. 15. 



This species is distinguished from P. globuliferum by the loose 

 capillitium, the large irregular lime-knots, and the absence of a 

 definite columella, although traces of the latter are sometimes V 

 present. It forms small colonies on dry leaves, often associated 

 with Didymium sqiiamulosiim, which it resembles superficially, so 

 that it is often overlooked by inexperienced collectors. The hy- 

 pothallus may be absent, and the stalks thinner or stained, but 



