Jackson : New Rusts on Carduaceae 



109 



Puccinia Parthenii Arth. Bull. Torrey Club 37: 570. 1910 



This name was based on Uredo Parthenii Speg., which was 

 described in 1899 from a uredo on Parthenium Hysterophorus L. 

 Telia were found by Dr. Arthur on two collections on P. argen- 

 tatum A. Gray made by F. E. Lloyd in Mexico. With these col- 

 lections were included one uredinial collection on P. Hysterophorus 

 from Mexico State (Holway 3228) and one on P. incanum H.B.K. 

 from Texas (Tracy & Earle 324a). 



A recent study made by the writer has led to the conclusion that 

 two distinct species were probably included. The urediniospores of 

 the collection on P. Hysterophorus are quite different from those 

 on P. argentatum. On the former they are obovate or triangular, 

 20-24 by 24-28 fx, with walls 1.5-2.5 /x thick, minutely and sparsely 

 echinulate, the pores 3, one in apex and two subequatorial, while 

 on the latter they are globoid or ellipsoid, 20-23 by 23-32 /x, the 

 walls 3-3.5 n thick, finely and moderately echinulate, the pores 2 

 or 3, approximately equatorial. 



Parthenium Hysterophorus, as noted above, is the type host for 

 Uredo Parthenii Speg. Unfortunately this has not been seen, and 

 it has not been possible to determine with certainty whether or not 

 the uredinial collection made by Holway in Mexico is identical. 

 It seems best, however, to exclude Uredo Parthenii Speg. from 

 Puccinia Parthenii Arth. for the present and to tentatively assign 

 to it the Mexican collection on P. Hysterophorus. The collection 

 made by Lloyd at Mazapil, state of Zacatecas, Mexico, March 27, 

 1908, on P. argentatum should be taken as the type of Puccinia 

 Parthenii Arth. as emended. 



This name was published by Dr. Arthur at our request as a sub- 

 stitute for the name P. Coreopsidis Jackson & Holway, which was 

 based on a Guatemalan collection determined as on Coreopsis mexi- 

 cana (DC.) Hemsl. It happened that the name P. Coreopsidis was 

 used by Miss E. Wakefield for an entirely different rust (a micro- 

 Puccinia) on Coreopsis from Uganda, tropical Africa, four months 

 previously (cf. Bull. Misc. Inf. Kew 1918: 209. Aug. 1918). 



Recently the writer had occasion to compare P. additicia with 



Puccinia additicia Jackson & Holway 



