DiDYMIUM 123 



Distribution: *California, Colorado, Florida, Iowa, Kansas, 

 New York, North Carolina, *Ohio, Ontario, *Oregon, *Pennsyl- 

 vania, Quebec, South Carolina, ""Washington, ^Wisconsin. 



Illustration: Lister, Mycetozoa ed. 3. pi. 108. 



This species is not at all rare, but forms small colonies so 

 that it may be overlooked. It is distinguished from D. melano- 

 spermum, which also has dark stalks, by the shape of the spo- 

 rangia and absence of a definite columella. It also superficially 

 resembles Physarum megalosporum, but the generic characters 

 are different. 



9. Didymium melanospermum (Pers.) Macbr. N. A. Slime- 

 Moulds 88. 1899. 



Physarum melanospermum Pers. Neues Mag. Bot. 1: 88. 1794. 

 Didymium farinaceum Schrad. Nov. Gen. PI. 22. 1797. 

 Physarum sinuosum Link, Ges. Nat. Fr. Berl. Mag. 3: 27. 1809. 



Plasmodium colorless or gray (Lister). Total height 0.5 to 

 1 mm. Sporangia gregarious, subglobose or hemispherical, 

 deeply umbilicate beneath, 0.7 to 1 mm. diam., stalked or sessile, 

 often confluent, and occasionally forming flattened plasmodio- 

 carps, white or gray; sporangial wall firm, clothed with stellate 

 crystals of lime. Stalk cylindrical from a broad base, striate, 

 dark brown, occasionally rufous or partly so, 0.2 to 0.7 mm. long, 

 0.05 to 0.2 mm. thick, opaque and granular from enclosed refuse 

 matter, sometimes containing crystalline nodules of lime. Colu- 

 mella large, hemispherical, umbilicate, dark brown, rarely whit- 

 ish, chambered, containing irregular nodules of lime. Capillitium 

 of stout, sparingly branched or simple, flexuose threads, colorless 

 or purplish brown, often showing dark, calyciform thickenings. 

 Spores dark purplish brown or purplish gray, with thick spore- 

 walls, nearly smooth or spinose, 9-12 ;u diam. 



Var. minus Lister, Mycetozoa ed. 2. 129. 1911. 



Didymium farinaceum Schrad. var. minus Lister, Mycetozoa 97. 1894. 



Didymium minus (Lister) Morg. Jour. Cin. Soc. Nat. Hist. 16: 145. 1894. 



Sporangia smaller; threads of capillitium slender; spores 

 smaller, 7-9 /x diam. 



Var. bicolor G. Lister, Mycetozoa ed. 3. 115. 1925, 



Columella and upper part of stalk nearly white from enclosed 

 calcareous deposits. 



Type locality: Europe. 



