Physarum 45 



Sporangia gray or pale yellow; lime-knots pale yellow. 



Var. Bethelii (Macbr.) Sturg. Colo. Coll. Pub. Sc. Ser. 12: 439. 1913. 

 Physarum Bethelii Macbr.; Lister, Mycetozoa ed. 2. 57. 1911. (N. Y. B. G. 

 nos. 7325, 9969, type material.) 



Sporangia subglobose, umbilicate beneath, pale yellow or iri- 

 descent blue from absence of lime; capillitium a dense network 

 with large, irregular, pale yellow lime-knots. 



Type locality: France. 



Habitat: On dead wood; common. 



Distribution: The typical form, var. aurantium, and var. 

 incanum are abundantly distributed throughout North America; 

 var. Bethelii, Colorado and New York. 



Illustrations: Lister, Mycetozoa ed. 3. pi. 31, 200. 



Collections are sometimes made with branching stalks, each 

 branch carrying a sporangium, and these may be of different 

 shades of color on one stalk. Var. hinnuleum G. Lister has not 

 yet been found in North America. It has reddish brown lime in 

 the sporangial walls and lime-knots, with buff-colored stalks 

 enclosing lime. Buff, as applied to the spores of the variety in 

 the Lister Monograph, is a clerical error. Occasional colonies of 

 P. viride have reddish orange lime, but no calcareous stalks. 

 From this the color shades in all gradations to the almost white 

 phases of var. incanum, some of which are difficult to distinguish 

 from P. nutans, as there is little but color distinction between the 

 two species. P. viride usually has paler spores than P. nutans. 



18. Physarum rigidum G. Lister, Mycetozoa ed. 3. 36. 1925. 

 Physarum viride (Bull.) Pers. var. rigidum Lister, Mycetozoa ed. 2. 56. 1911. 



Plasmodium yellow (Lister). Sporangia gregarious, discoid, 

 often umbilicate above, yellow, dull orange, or iridescent from 

 absence of lime, stalked. Stalk slender, orange or yellow above, 

 dark below from included refuse matter, 0.3 to 1.5 mm. high. 

 Capillitium of sparingly branched threads or flattened tubes with 

 long, narrow, orange lime-knots, or consisting almost entirely of 

 slender, rod-like tubes enclosing lime-granules. Spores rich 

 violet-brown, minutely spinulose, 9-10 n diam. 



Type locality: Japan. 



Habitat: On dead wood. 



Distribution: *West Indies. 



