PHYSARUM 91 



from the field and maturing under a bell-jar, the color changes to a 

 watery white just before the sporangia rise in fruit. 



As Sphcerocarpus albus, Bulliard first prescribed the limits by which 

 the species is at present bounded. The description by Fries (Syst. 

 Myc. 3 : 128) is especially graphic: "Peridium very thin, in form quite 

 constantly lenticular, umbilicate at base, at first smooth, then uneven, 

 generally laciniate-dehiscent, the segments persistent at least at base." 

 Physarum album Fr. (Syst. Myc. 3 : 147) is regarded as a synonym of 

 Didymium difforme and should not be revived for a different species, 

 hence Persoon's name, generally accepted, should stand. P. album 

 Fuckel (Rhen. Fl. No. 1469, 1865), is believed to be P. cinereum. 



Var. robustum Lister is applied to an erect, sometimes plasmodiocar- 

 pous form, often exhibiting a pseudocolumella. 



Common and world-wide in distribution. 



73. Physarum viride (Bull.) Pers. 



Usteri Ann. Bot. 15 : 6. 1795. 

 PI. VI, Figs. 127, 128. 



1791. Sphcerocarpus viridis Bull., Champ. 135. 



1791. Sphcerocarpus luteus Bull., Champ. 136. 



1791. Stemonitis viridis (Bull.) Gmel., Syst. Nat. 2 : 1469. 



1794. Physarum aureum Pers. in Roemer, Neu. Mag. Bot. 1 : 88. 



1829. Physarum nutans var. viride Fr., Syst. Myc. 3 : 129. 



1829. Physarum nutans var. aureum Fr., Syst. Myc. 3 : 129. 



1875. Tilmadoche mutabilis Rost., Mon. 129. 



1880. Tilmadoche viridis (Bull.) Sacc, Michelia 2 : 263. 



Sporangia globose, flattened or lenticular, 0.3-0.5 mm., plane or 

 concave below, variously colored — yellow, greenish yellow, rusty 

 orange — stipitate, nodding; the peridium splitting irregularly or 

 reticulately; stipe subulate, variable in length and color, through 

 various shades of yellow and red to black; capillitium strongly de- 

 veloped, concolorous with sporangium, the colorless tubes connecting 

 the yellow or orange fusiform nodes; spores smooth, fuscous or violet- 

 black, 7-9 fx. Plasmodium yellow to yellow-green. 



A very handsome and common little species ; like the preceding, but 

 generally greenish yellow in color, and occasionally brilliantly orange 

 without a suggestion of green. Indeed, the color is so variable that 

 some authors have been disposed to discard the species entirely, inas- 

 much as the chief specific character is color. 



The following varieties may be recognized : 



Var. aurantium (Bull.) Lister, Mycetozoa 47, 1894 (SphcErocarpus 

 aurantius Bull., 1791; Slemonitis aurantia (Bull.) Gmel. 1791; Phy- 

 sarum aurantium (Bull.) Pers., 1801; Trichia aurantia (Bull.) DC, 



