Physarum , 67 



This species forms large colonies of many small clusters spread- 

 ing over a wide area on piles of decaying vegetation. It connects 

 the genera Fuligo and Physarum, being intermediate between 

 F. septica and P. polycephalum, and is often associated with the 

 latter species on the same habitat. Other forms of an aethalioid 

 nature, small and solitary, and on other habitats like stumps, 

 twigs, and dry leaves, are found occasionally. They have a 

 labyrinthine structure, but it is continuous, and not broken into 

 small, uniform clusters. They have often been regarded as 

 plasmodiocarps of P. gyrosum, and while they appear to connect 

 it with F. septica, the habit is aethalioid, and they belong with 

 F. septica as mentioned under that species. Without their in- 

 clusion, P. gyrosum is a sharply defined form, but may at times 

 form something like plasmodiocarps by the confluence of many 

 rosettes, and associated with the separated ones. 



45. Physarum Famintzini Rost. Mon. 107. 1874. 



Physarum Gulielmae Penzig, Myx. Buit. 34. 1898; Lister, Mycetozoa ed. 2. 

 76. 1911. 



Plasmodium orange (Lister). Sporangia subglobose or reni- 

 form, sessile, about 0.4 mm. diam., brownish orange or chestnut- 

 brown, rugulose, clustered or heaped, with a colorless or yellow, ■ 

 membranous hypothallus; sporangial wall stout, somewhat carti- 

 laginous, with abundant clustered deposits of brownish yellow 

 lime-granules. Capillitium an elastic, expanding network of 

 hyaline threads, with large, white, angular or branching lime- 

 knots, sometimes forming a pseudo-columella. Spores purplish 

 brown, spinulose, 10-12 m diam. 



Type locality: Poland. 



Habitat: On herbaceous stems, twigs, etc. 



Distribution: *Maryland. 



Illustration: Lister, Mycetozoa ed. 3. pi. 63. 



The characteristic feature of the closely clustered sporangia 

 is the elastic capillitium which expands at maturity to twice the 

 height of the sporangium. The only North American record is 

 by Macbride & Martin (Myxomycetes 52. 1934) and based on 

 five sporangia among the sporangia of Didymium squamulosum 

 on a specimen in the United States National Herbarium. The 

 authors, in their description of the species, do not mention the 

 unusual capillitium, which is otherwise unknown in the genus. 



