Physarum 77 



60. Physarum virescens Ditm. in Sturm, Deutsch. FI. Pilze 1: 



123. 1817. 



Plasmodium lemon-yellow (Lister). Sporangia irregularly 

 obovoid or ellipsoid, 0.2 to 0.4 mm. diam., sessile, heaped and 

 superimposed in small clusters, rugose, yellow or greenish yellow; 

 sporangial wall membranous, with dense included clusters of 

 yellow lime-granules, rarely without lime. Capillitium a net- 

 work of hyaline threads with fusiform or irregular, yellow lime- 

 knots. Spores pale violet-brown, minutely spinulose, 7-10 /i 

 diam. (Plate 8, fig. 4.) 



Type locality: Germany. 



Habitat: On dead leaves, mosses, and twigs. 



Distribution: Common and abundant in the United States 

 and Canada. 



Illustration: Lister, Mycetozoa ed. 3. pi. 61, figs. a~c. 



As described, this species is restricted to the small, heaped, 

 yellow or greenish yellow sporangia of irregular shape. Var. 

 nitens Lister, regarded here as synonymous with P. luteolum, is a 

 much larger form which is never heaped or superimposed, and 

 with a bright yellow color. Var. obscurum Lister, as the name 

 implies, covers certain obscure forms, rarely found, which prob- 

 ably belong with related species but cannot be placed accurately. 

 As a rule they have some aspects of imperfect or abnormal de- 

 velopment, such as lack of lime, hardening, or otherwise. P. 

 virescens forms many developments of numerous clusters at one 

 time in wet places. 



61. Physarum digitatum G. Lister & Farquh.; G. Lister, Jour. 

 Bot. 54: 128. 1916. 



Physarum thejoleum Morg. Jour. Cin. Soc. Nat. Hist. 19: 22. 1896. Not 



P. thejoteum Fries. 1818. 

 Physarum instratum Macbr. N. A. Slime-Moulds ed. 2. 62. 1922. 



Plasmodium grayish yellow (Lister). Sporangia closely clus- 

 tered, sessile, and subglobose, obovoid, or ellipsoid, simple or 

 branched and irregularly lobed, 0.2 to 0.4 mm. diam., tawny yel- 

 low or light brown, roughened, seated on a membranous hypo- 

 thallus; sporangial wall membranous, with abundant deposits of 

 pale yellowish brown lime-granules. Capillitium a network of 

 hyaline threads with fusiform or angular, pale yellowish brown 

 lime-knots, which may unite to form a pseudo-columella. Spores 



