PHYSARUM 97 



peared to sustain little injury and ultimately developed normal 

 sporangia." 



55. Physarum nutans Pers. 



1791. Sphaerocarpus albus Bull,, Champ., p. 137, t. 407, III., and t. 470, 

 I, A-L. 



1791. Stemonitis alba (Bull.), Gmel., Syst. Nat., p. 1469 (?). 



1795. Physarum nutans Pers., Ust. Ann. Bot., XV., p. 6. 



1803. Trichia cernua Schum., Enum. PL, SaelL, II., p. 241. 



1829. Physarum cernuum (Schum.) in part, Fr., Syst. Myc, III., pp. 130, 

 147. 



1848. Tilmadoche cernua (Schum.) Fr., Summ. Veg. Sc, p. 454. 



1873. Tilmadoche nutans (Pers.) Rost., Versuch, p. 10. 



1899. Tilmadoche alba (Bull.) Macbr., N. A. S., p. 58. 



1911. Physarum nutans Pers., List., Mycet., 2nd ed., p. 67, in part. 



Sporangia gregarious, depressed-spherical, stipitate, umbilicate, 

 gray or white, thin-walled, nodding; stipe long, tapering upward, 

 brown or black below, ashen white above, lightly striate, graceful ; 

 capillitium abundant, threads delicate, intricately combined in loose 

 persistent network with occasional minute, rounded, or elongate cal- 

 careous nodules; spores minutely roughened, globose, about 10 /t. 



The nodding, lenticular, umbilicate sporangium, barely attached to 

 the apiculate stipe, is sufficient to distinguish this elegant little spe- 

 cies, recognized and quite aptly characterized by mycologists for more 

 than one hundred years. As Sphaerocarpus albus Bulliard first pre- 

 scribed the limits by which the species is at present bounded. The 

 description by Fries {Syst. Myc, III., 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." 



The stipe is usually white above, fuscous below, at the apex almost 

 evanescent; hence the cernuous sporangia. The same character is 

 less strikingly manifest in the species next following. 



The Plasmodium is bright yellow, sometimes greenish. Brought in 

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

 watery white just before the sporangia rise in fruit. P. album 

 Fuckel, Rhen. FL, No. 1469, 1865, is believed to be P. cinereuni 

 (Batsch) Pers. 



8 



