Vol. xiv. No. 6.-Botanical Gazette -June, 1889. 



Sub-epidermal rusts 



H. L. BOLLEY. 



(with platp: xv.) 



During the past } r ear I have made a structural study of 

 the teleutosporic stage of Puccinia coronata Cda. and P. ru- 

 bigo-vera DC. upon different hosts with the hope that care- 

 ful work would reveal, among other things, some differentia- 

 ting structural characteristics. To be of worth, such defining 

 marks must be constant through all variations of an individ- 

 ual species. Though the work was not wanting in interest, 

 it may be well to say that, with regard to the discovery of 

 such diagnostic features, my observations have been essen- 

 tially negative ; for structural variations which upon some 

 hosts were often quite marked were upon others either absent 

 or so slight as to be of no comparative value. 



In most species of Uredinese, the teleutospores break 

 through the epidermis of the nourishing plant (tig. i), but in 

 both the species mentioned they reach maturity in the matrix 

 or sorus without rupturing the enclosing epidermis (fig. 2), a 

 condition which is typical of a number of other species, which, 

 for convenience in this paper, have been termed k ' sub-epider- 

 mal." 1 



These species, because of their similarity of development, 

 present many common peculiarities of form and structure. 

 In some cases, as P. coronata and P. rubigo-vera, species 

 grade the one into the other so closely as to nearly defy sep- 

 aration upon a structural basis. Upon examining type spores 

 of these two forms, one immediately notices the striking dif- 

 ferences in the apices, P. coronata being possessed of a crown 

 of flame-yellow finger-form projections, while those of P. ru- 

 bigo-vera are truncate (fig. 13 and 12, a and b). These, 

 however, are not constant characteristics. Some specimens 

 of P. rubigo-vera produce teleutospores which show a strong 



tendency to form points, and many specimens of P. coro- 



