Physarum 35 



Sporangia sessile or forming simple, curved, or branching 

 plasmodiocarps. 



Type locality: Germany. 



Habitat: On dead leaves and wood; not rare. 



Distribution: Widely distributed throughout the United 

 States; Ontario, Puerto Rico, Quebec. 



Illustrations: Lister, Mycetozoa ed. 3. pi. 21, 65. 



There are no differences between P. sulphiireum and P. varia- 

 bile Rex sufficient to regard them as distinct. Var. sessile is 

 unworthy of varietal rank, and is placed here merely to assist in 

 clearing the confusion about the various phases of P. sulphureum. 

 The sessile and plasmodiocarpous forms are usually found when 

 the species is fruiting in abundance. When separated or isolated, 

 it is often difficult to distinguish them from P. Serpula Morg. 

 The plasmodiocarps are stouter, shorter, and darker than those of 

 P. Serpula, and the spores are a little smaller. P. sulphureum 

 forms single colonies with much variation in color and sporangial 

 shape. P. Serpula usually appears in many small developments 

 at one time. 



4. Physarum Listeri Macbr. ; Macbr. & Martin, Myxomycetes 62, 

 1934. 



Physarum luleo-album A. & G. Lister, Jour. Bot. 42 : 130. 1904. (N. Y. B. G. 

 nos. 10906, 10907, authentic material.) Not P. luteo-album Schum. 1803. 



Plasmodium orange (Lister). Sporangia gregarious, stalked, 

 smooth or rugulose, subglobose, about 1 mm. broad, 0.7 mm. high, 

 yellow shading into white, deep orange, or olivaceous; sporangial 

 wall pale yellow or orange, with deposits of yellow lime-granules, 

 often dense and compacted to form an outer separable wall, per- 

 sistent at the base. Stalk stout, smooth, 0.5 to 1 mm. long, 

 bright yellow, orange, or reddish brown, usually paler below, 

 cylindrical, tapering upward or narrowed below, charged with 

 lime-granules throughout, or the lime in the form of crystalline 

 nodules toward the base. Columella large, subglobose or shortly 

 clavate, pale yellow or orange. Capillitium radiating from the 

 columella and persistent after dispersal of the spores, of slender, 

 straight, pale yellow threads, branching at acute angles, or netted 

 and anastomosing; lime-knots either few or many, yellow, small 

 and rounded, or spindle-shaped, or large and angular. Spores 

 purplish brown, strongly spinulose, about 12 /x diam. 



Type locality: Italy. 



