PHYSARUM 53 



small size of the heaped sporangia. It resembles some phases of 

 P. virescens where the sporangia are small and somewhat heaped or 

 rather aggregated, and scantily supplied with lime; but in such case the 

 lime is yellow and the spores are small. 

 Not uncommon, especially eastward; occurring also in Europe. 



15. Physarum lepidoedeum Gilbert 



Am. Jour. Bot. 19 : 133. 1932. 



Sporangia sessile, solitary or in small groups, on black waste matter 

 forming a small hypothallus, irregularly globose, 0.5 to 1.2 mm. in 

 diameter, with a tendency to form small crowded plasmodiocarps; 

 peridium blue-gray, membranous, iridescent, with a thin layer of flat, 

 more or less rounded lime-scales similar to those of Lepidoderma; 

 capillitium a dense net of colorless threads, the lime-knots white, con- 

 spicuous but not abundant, medium sized, rounded or with points 

 meeting the capillitial threads, a few sometimes larger and more 

 angled; spores dark purple in mass, globose, under the lens bright 

 violet, uniformly finely warted, 12-14 ix in diameter. 



The Lepidoderma-like peridium is distinctive. The spores are larger 

 than in most physarums and very uniform in size. 



Oregon : on old kale stalks in a pile of herbaceous waste. 



16. Physarum nudum Macbride 



Am. Jour. Bot. 19 : 134. 1932. 



Sporangia sessile, globose or somewhat plasmodiocarpous, occa- 

 sionally with a pallid, slender, usually prostrate stipe, 0.4-0.7 mm. in 

 width; peridium single, limeless, dark gray, somewhat iridescent; 

 hypothallus scanty, reticulate, membranous, hyaline, connecting the 

 lines of sporangia; columella none; capillitium sparse and nearly or 

 quite limeless, composed of slender thread-like tubules here and there 

 expanded into hyaline vesicular structures; spores violet-black in mass, 

 clear violet under the lens, minutely roughened, 9.5-11 /x in diam- 

 eter. 



A specimen collected by T. H. Macbride in Washington in 1916, was 

 marked as a new species under this name. Another specimen, collected 

 by Mr. H. C. Gilbert in May, 1930, near Salem, Oregon, proved to be 

 the same. In its limeless character it suggests P. confertum, but differs 

 in size, color and habit of growth; it suggests also limeless forms of 

 P. didermoides but is different in habit, and with smaller, lighter 

 colored, much smoother spores. Mr. Gilbert notes that the sporangia 



