^oiDiAL stagp: and N()MP:NCLATUKE. 11 



which had not been artificially inoculated also produced aecidia.' In 

 1895 Eriksson again made inoculation experiments on the barberry 

 with the teleutospores of this rust, but in 25 inoculations none was 

 successful.- In this country Kern ^ in 1908 observed eight unsuccessful 

 inoculations on the barberry. 



From their results Eriksson and Henning concluded that timothy 

 rust does not form its secidial stage on the barberry, while Kern ^ 

 says that "The one positive result mentioned ought, it seems, [to] be 

 accorded more weight than all the negative ones together, and proves 

 that it [timothy rust] does, even if with difficulty, form its secial 

 stage upon the barberry." Eriksson and Henning regard the rust as 

 a distinct species and name it Puccinia pJilei-pratensis , while Kern 

 considers it "a race of Puccinia poculiformis (graminis) or a so-called 

 physiological species." Evans accepts the name Puccinia pUei- 

 pratensis,* and in a discussion of the development of the uredo mycelia 

 of the cereal rusts shows that there are differences in the details of 

 infection of this rust and Uredo graminis, wliich, although slight, are 

 well marked. In a later paper Kern ^ states that he is still of the 

 opinion that this rust is not entitled to specific rank and would 

 include it under "Puccinia poculiformis (Jacq.) Wettst.," i. e., Puc- 

 cinia graminis Pers. He modifies his previous statement as to its 

 being a physiological species and thinks it might better be considered 

 a variety or subspecies, ''since it does, as previously pointed out, 

 possess some slight morphological difi'erences from the typical form, 

 particularly in the smaller secial cups and the more deHcate uredinial 

 mycelium." 



From the physiological specialization of this rust, as shown in 

 experiments above reported ; from its distinctive method of infection 

 from the uredospore, as described by Evans; from the diflSculty with 

 which it produces its secidium on barberries, as shown by Eriksson 

 and Henning; and from the delicacy of the mycelium of the uvedo 

 stage as compared with the typical graminis form, as cited by Kern, 

 it is evident that the rust of timothy has many distinctive character- 

 istics, and, even if not well fixed, is highly specialized. Whether or 

 not it should be regarded as a distinct species is, perhaps, debatable. 



1 Eriksson, Jakob, and Henning, Ernst. Die Getreideroste, 1894, p. 137. 



2 Eriksson, Jakob. 1st der Timotheengrasrost eine selbstandige Restart odor nicht? Ofversigt af 

 Kongliga Svenska Vetenskaps-Akademiens Foriiandlingar, no. 5, 1902, p. 191. 



« Kern, F. D. Tlie Rust of Timotliy. Torreya, vol. 9, January, 1909, p. 4. 



< Evans, I. B. Pole. The Cereal Rusts. The Development of Their Uredo Mycelia. Annals of Botany, 

 vol. 21, no. 84, 1907, pp. 446-448. "The substomatal vesicle is a very definitely shaped body closely re- 

 sembling that of J7rfdo graminis, but narrower * * *. It differs from f/rcdograTT?!?;/.? chiefly in the" fact 

 that the end from which the hj-pha springs does not cling to the head of the guard cell."' 



sKem, F. D. Further Notes on Timothy Rust. Proceedings of Indiana Acadsmy of Science, 1909 pp. 

 417-418. 



224 



