116 



Mycologia 



P. Zinniae Sydow, on Zinnia tenuiflora, from Jalisco. 



P. Diaziana Arth., on Ximenesia encelioides, from Coahuila. 



P. Tridacis Arth., on Tridax procumbens, from Cuba. 



P. Eleuther anther ae Diet., on Eleuther anther a ruderalis, from the 



West Indies and Panama ; also in South America. 

 P. Tetranthi Sydow, on Tctranthus hirsutus, from Haiti. 



It will be noted that each one is known in North America on a 

 single host species, and all are on separate genera. To these 

 should be added unnamed forms on Parthenium Hysterophorus 

 from southern Texas and on Spilanthes oleracea from Martinique. 

 The latter might possibly be properly referred to Puccinia Spi- 

 lanthicola t Mayor. 



A careful comparison of these forms has failed to reveal any 

 method by which they can be separated on a morphological basis 

 and it has been decided to treat them as one species in the North 

 American Flora. It is possible, indeed quite probable, that they 

 are biologically distinct and may even have had, in part, an inde- 

 pendent origin. It seems reasonable to suppose that collectively 

 or independently they are correlated with one or more cyperaceous 

 rusts occurring in the same region, which have aecia on these or 

 related hosts, but the genetic connection of which has not yet been 

 determined. 



It should be pointed out that this species is very much like P. 

 Emiliae P. Henn. (see p. 119), which occurs on members of the 

 tribe Senecioneae with a similar distribution. It is also related to 

 Puccinia Silphii S'chw., which occurs on Silphium sp. in temperate 

 regions, but which has somewhat narrower spores. 



The synonymy, etc., is as follows : 



Puccinia Melampodii Dietel & Holway; Holway, Bot. Gaz. 24: 



32. 1897 



Puccinia solida Berk. & Curt. Tour. Linn. Soc. 10 : 356. 1869. 



Not P. solida Schw. 1839. 

 Puccinia Synedrellae Lagerh. ; Sydow, Ured. 376, hyponym. 1890. 

 Puccinia Synedrellae P. Henn. Hedwigia 37 : 277. 1898. 

 Dicaeoma cub ens e Kuntze, Rev. Gen. 3 3 : 466. 1898. 

 Dicaeoma Synedrellae Kuntze, Rev. Gen. 3 3 : 470. 1898. 



