36 Arthur : Amphispores of grass and sedge rusts 



given by Carleton * in 1901, are on the contrary resting spores, 

 and possess thick, indurated walls, colorless contents and per- 

 sistent or semi-persistent pedicels. The sori appear to the naked 

 eye, and under a hand lens, like those of the teleutospores, for 

 which they are often mistaken. This mistake has, in a number 

 of instances, led to their description as species of Uromyces ; thus 

 U, Brandcgei Pk., U. simulans Pk., U. scabcr E. & E., U, Caricis 

 Pk., and U. atrofusca DudL & Th., are names of the amphisporic 

 stages of different species of Pticcinia. Amphispores can always 

 be told from true teleutospores, however, by possessing two or 

 more germ pores, while teleutospores have but one, and that is 

 usually not discernible except at time of germination, 



■ Amphispores appear to belong to species having their main 

 development in arid or semi-arid regions. They give to the 

 uredospore the same power to tide over unfavorable periods of 

 growth that is usually possessed only by the teleutospore, and 

 with the additional advantage that when the inhibiting period is 

 past they can infect the same host from which they were derived, 

 whereas the teleutospore can only Infect an alternate host of a dif- 

 ferent species. 



Up to the present time no species found to possess amphi- 

 spores is known outside the United States and Mexico, wdth the 

 single exception of an Indian species occurring in the Himalayas. 

 Most of the collections have been made in the semi-arid regions 

 of North America, Because this form of spore is not usually 

 recognized, and not well understood, the writer presents the fol- 

 fowing notes and illustrations, drawn from specimens in his her- 

 barium. 



I. PucciNiA VEXANS'Farl. {Uromyces Brandegci Pk.) has 

 globoid uredospores with golden yellow, thin w^alls, minutely 

 echinulate, and showing eight scattered germ pores. Their pale 

 color makes them comparatively inconspicuous, moreover they are 

 but sparingly produced, and in consequence but rarely collected. 



The amphispores are much larger than the uredospores, obo- 

 vate, semiopaque, and with dark chestnut-brown walls, very thick, 

 much thicker above, densely verrucose, and possessing four germ 

 pores which are symmetrically arranged in a circle just below the 



* Science II. 13 : 249. 



