PAPERS GIVING RUSTS OF NORTH AMERICA. 203 



The rust is the nredinial stage of Uromyccs Caladii (Schw.) 

 FarL, the aecial stage being given under nos. 2860 and 2861, and the 

 tehal stage under no. 2946. Doubtless Schweinitz was right in 

 thinking the host to be Arum z'irginicum L., now known as Pel- 

 tandra virginica (L.) Kunth, and not Caladiiim [sagittifoliitm 

 Nutt.], although the fact can not now be verified. Both hosts occur 

 in North Carolina, but only the former in Pennsylvania. 



2840. 30. C. U. Spermacoces L.v.S., Syn. Car., [under] Puccinia, 502, Lk. n. 



57, elegant. Spores not septate, and Philadelphia. 

 (502. 17. [Puccinia] Spermacoces Sz. 



P. subquadrate, dark chestnut-brown, spores globose, simple, 

 pedicel very long, fiHform. 



Frequent on leaves and stems of Spermacoce. Breaks through 

 the epidermis in the form of a square. Spores fuscous, irregularly 

 globose, pointed or blunt, without septum. Pedicel ten times longer, 

 hyaline. By pressure ■ the epidermis is separated from the square 

 mass as a continuous membrane in which a cellular structure is not 

 to be seen under lenses having a focus of half a line, and a very 

 thin vesicular substance escapes.) 



Represented by two small fragments of stem with leaves and 

 fruit, placed loose in a mounted packet. The original empty packet 

 is labelled inside " Dicseoma Spermacocis Salem," and on the out- 

 side " Caeoma Spermacocis LvS. Sal." 



The rust is chiefly the telial stage of Uromyccs Spermacoces 

 (Schw.) M. A. Curt., common throughout the southern states, and 

 the host is undoubtedly Diodia teres Walt. {Spermacoce diodina 

 Michx.). 



It is interesting to trace the change in view, in the interim be- 

 tween the publication of the two papers, regarding the systematic 

 position of forms with dark teliospores, which we would now call 

 Uromyccs. In the North Carolina paper of 1822 Schweinitz di- 

 vided the genus Puccinia into "A, spores distinctly bilocular," and 

 " B, spores globose with septum inconspicuous," evidently following 

 the example of DeCandolle in the Flore Francaise (2 1224) of 1805. 

 Under the latter division Schweinitz placed two species of Uro- 

 myccs, with the septum described as absent or not conspicuous, re- 

 spectively. Evidently there was a feeling that these forms with an 

 uncertain septum and globoid spore belonged with those species of 



