PUCCINI A VEXANS FARL. 23 



The species was first described by Peck as a Uromyces ( TJ. hrandegei 

 Pk.) rt on the basis of material collected by Mr. T. S. Brandege, in 

 which specimens contained only the third s'pore form. Because of the 

 discovery afterwards of two-celled spores associated with this third 

 spore form, even sometimes in the same sorus, Doctor Farlow described 

 it as a Puccinia {P. vexans Farl.) in the Proceedings of the American 

 Academy of Arts and Sciences, Vol. XVIII, pp. 82-83. At that time 

 the true uredo stage had not been discovered. 



This third spore form is far more prevalent than either of the others 

 as a rule, but is sometimes entirely absent, leaving only the teleuto 

 stage. It is distinct from either of the other forms in structure and 

 appearance, and yet resembles both in some respects. It is larger than 

 either of them, is strongly papillate, and has a much thicker cell wall, 

 but on the other hand possesses the color and persistence of pedicels 

 of teleutospores and appears to have pores like the uredospores. (PL 

 II, fig. 5.) Doctor Farlow, in his description, says: 



A species in which some of the sori contain only two-celled spores must certainly 

 be held to be a Puccinia, and the perplexing question arises, are the one-celled spores 

 a unilocular form of teleutospores similar to what is known in P. cesatii Schr., or are 

 they the uredospores of this species? ■ I have not been able to find any other spores 

 which represent the uredo of the species; and 'never having seen the unicellular 

 spores in germination, there is, so far as we yet know, no reason why they may not 

 be the uredospores. On the other hand, their general appearance and the density 

 of the cell wall would lead one to suppose that they were of a teleutosporic nature. 

 Further conjecture is unnecessary, because, as the species is not at all rare in some 

 localities, botanists who can examine the fungus on the spot ought to be able to 

 ascertain whether the one-celled bodies produce promycelia or not, or else to discover 

 the true uredo of the species. 



A full description of all three forms is given by Arthur and Holway 

 in Descriptions of American Uredinea^ accompanying Fasicle IV of 

 Uredineae Exsiccatae et Icones. 6 



After numerous unsuccessful trials during several years, the writer 

 was finally able to germinate the third spore form, and, as suggested 

 by Doctor Farlow, has in this way been able to determine its nature. 

 In manner of germination it is exactly like the uredospore, the long 

 simple germ tubes being produced through equatorial pores (PI. II, 

 figs T and 8), but is like the teleutospore in germinating onty after a 

 dormant period and exposure to extremes of weather. The uredo and 

 teleuto forms being already present and morphologically different 

 from this form, it must be considered distinct. Because of the dual 

 nature of this spore form, the writer has already- proposed for it the 

 name amphispore in a paper read before the Baltimore meeting of the 

 Society for Plant Morphology and Physiology in 1900, only an abstract 

 of which was published/ The term has since been adopted b} r Arthur 



«Bot. Gaz., 4: 127. 



6 Bui. Lab. Nat. Hist. State Univ. Iowa, Vol. V, pp. 329-330. 



c Science, Vol. XIII, p. 250. 



