Physarum nucleatum

Physarum nucleatum Rex, Proc. Acad. Phila. 1891: 389. 1891
Sporangia stipitate, spherical, white, about 0.5 mm. in diameter, erect or nodding ; peridium membranous, studded with rounded, white calcareous nodules, the lime sometimes scanty and the peridium then metallic, the lower portion thicker and remaining as a collar on the stem after the upper portion has disappeared; stalk subulate, yellowishwhite, rugose, not calcareous, about 1 mm. long; columella none; capillitium dense, white, the nodes small, white, rounded, aggregated in the center to form a conspicuous ball of lime, free from the stalk ; spores black in mass, violet-brown by transmitted light, minutely spinulose, 6-7 ^ in diameter.
Type locality: Philadelphia, Pennsylvania. Habitat: Dead wood.
Distribution: New York to Oregon, south to Nicaragua; Europe; South Africa; Japan; and generally in the tropics.