PHYSARUM 45 



3. Physaruin (Persoon) Rost. 



1794,1 Physarum Pers., Rom. Neu. Mag. f. d. Bot., I., p. 88, in part. 



1795. Physarum Pers., UsU Ann. Bot., XV., p. 5, in part. 



1801. Physarum Pers., Syn. Fung., p. 168, in part. 



1829. Physarum (Pers.) Fries, Syst. Myc, II., p. 127, in part. 



1875. Physarum (Pers.) Rost, Mon., p. 93. 



Sporangia plasmodfocarpous, aethalioid or distinct ; the peridium 

 usually simple, sometimes double, irregularly dehiscent, more or less 

 definitely calcareous; capillitium a uniform irregular net, dilated 

 and calcareous at the nodes, adherent on all sides to the peridial wall. 



This large and cosmopolitan genus is readily recognized by the 

 characters quoted. It may be added that the capillitial threads are 

 always exceedingly delicate, probably tubular, but never filled with 

 lime throughout; the peridium may be almost nude or encrusted 

 with lime, which, where present, is always amorphous, never crystal- 

 line; the sporangia when distinct may be either sessile or stipitate, 

 and the stipe in the latter case is often hollow and charged with 

 lime. In capillitium intermediate between Leocarpus and Badhamia, 

 since in the first the capillitium is unequally calcareous, diverse, while 

 in Badhamia the capillitium is intricate and calcareous throughout. 



As first set up by its founder, the genus included diverse forms, 

 only one or two of which would be included in the genus as now 

 limited.2 Persoon, however, was left to develop the matter to suit 

 himself, and in successive works gave, under this generic name, more 

 and more prominence to forms now so referred. Fries, Syst. Myc, 

 III., pp. 127 et seq., still better establishes the genus, though still in- 

 cluding forms that, judging from the description, seem to belong 

 elsewhere. Twenty years later Fries revising somewhat his earlier 

 work thought to improve the chances of future students by reducing 

 the number of physarums. This he would do by setting out cer- 

 tain evidently inter-related forms to make a new genus, Tihnadoche. 



1 Prior to Persoon the physarums were variously referred : Lycoperdon, 

 Sphaerocarpus, Trichia, etc. It seems unnecessary to quote the synonymy 

 further here. 



- Persoon's first-named species is P. aureum; see Romer Neu. Mag. f. d. 

 Bot., I., p. 88. 1794. 



