Physarum 41 



Physarum compactuni (Wing.) Lister, Mycetozoa 44. 1894. Not P. com- 



pactum Ehrenb. 1818. 

 Physarum columbinum (Rost.) Sturg. Mycologia 8: 200. 1916. Not P. 



columbinum Pers. 1796. 



Plasmodium light gray (Lister). Total height 1 to 2 mm. 

 Sporangia gregarious, scattered, or loosely clustered, stalked, 

 subglobose and flattened beneath, or hemispherical, 0.5 mm. 

 diam., erect or nodding, gray or bronze-colored, spotted with 

 white and iridescent between the spots, often dehiscing in petal- 

 like lobes; sporangial wall membranous, with numerous, sepa- 

 rated, rounded clusters of closely compacted Jime-granules. 

 Stalk 0.5 to 1.5 mm. long, erect or flexuose, subulate, furrowed, 

 thick at the base, white and densely charged with lime, often in 

 the form of granules or crystalline nodules, brown or black below 

 from included refuse matter. Columella none, replaced usually 

 by a calcareous ball near the base of the sporangium. Capillitium 

 abundant, of extremely delicate, branching and anastomosing 

 threads, without expansions at the axils, somewhat persistent, 

 white or pale bluish; lime-knots white, few, small, fusiform when 

 accompanied by the ball or cluster of lime, or uniformly dis- 

 tributed and larger and irregular when the cluster is absent. 

 Spores violet-brown, almost smooth, 7-9 ju diam. 



Type locality: Venezuela. 



Habitat: On dead wood; common. 



Distribution: Throughout North America. 



Illustration: Lister, Mycetozoa ed. 3. pi. 26, as P. colum- 

 binum. 



The rounded lime-clusters in the sporangial wall are some- 

 times replaced by crystalline scales as in the genus Lepidoderma. 

 This feature is also found occasionally in other species of Physa- 

 rum. The capillitium of P. Wingatense is not always persistent, 

 and being delicate, is liable to break away, leaving the persistent 

 base of the sporangial wall. Some phases appear somewhat like 

 varieties of P. nutans, but the central ball of lime and calcareous 

 stalk distinguish it therefrom; and P. nucleatum has the inner 

 cluster of lime, but a limeless stalk. 



13. Physarum mutabile (Rost.) Lister, Mycetozoa ed. 2. 53. 

 1911. 



Crateriachea mutabilis Rost. Mon. 126. 1874. 



Physarum Gilkeyaniim{?) Gilb.; Peck & Gilb. Am. Jour. Bot. 19: 133. 1932 



