OP THE UNITED STATES. 5 



older writers. The teleutospore condition was called Puceinia Graminis ; the uredo con- 

 dition Uredo linearis ; and the aecidial condition Aeoidium Berherldis. Recent writers 

 merely speak of the species Puceinia Graminis, including by that all the different stages. 

 To designate the old Aecidium Berheridis they say Puceinia Graminis, faugu? hymen- 

 iferus, and to designate the Uredo linearis they say Puceinia Graminis, fungus stylospor- 

 iferus. Or more briefly one says Puceinia Graminis (Uredo) or (Aecidium) as the case 

 may be. To understand at once what is meant by the different expressions one must be 

 acquainted with the literature of the development of the different species, and that is a diffi- 

 cult matter for us in America, since the observations on the subject are scattered in numer- 

 ous journals, some of which are seldom met with in this country. 



Since the development of Puceinia Graminis is probably as well known as that of any 

 species of the order, and is furthermore, the species in which the development was first 

 studied by De Bary, we may use that as a type in studying other members of the order. 

 The development is represented in four different stages, viz.: 



1. Teleutospores on grass in the autumn. 



2. Promycelium and Sporidia produced in spring directly from the teleutospores. 



3. The Aecidium produced in May or June on the harherry, comprising two sets of 

 organs, the Spermogonia with their spermatia and the cups or Aecidia proper. 



4. The TJredo produced on -grass from the spores of the Aecidia. 

 1. Teleutospores produced from the uredo-spores. 



There is a cycle of four different stages, which, taken together, constitute the life of the 

 individual Puceinia. It will be remarked that two of the stages are found on grass, one 

 on barberry, and one is produced directly from the teleutospores wherever they may be. 

 At present we are only interested in the genus Puceinia in so far as it is a type of the or- 

 der, and we must next see how far the other species of the order agree with Puceinia 

 Graminis. In the first place, if we consider the species of Puceinia alone, we find that 

 it is only in certain species that aecidial and uredo conditions are supposed to exist. In 

 some species, as P. Malvacearum Mont., only teleutospores are believed by some to occur. 

 In P. anemones Pers., uredo-spores are unknown ; in a large number of species aecidia 

 are unknown. Furthermore, in case of the species in which all the different stages are 

 known to occur, some have them all produced on the same hos1>plant, while others, as we 

 have seen in P. Graminis, bear them on different plants. It may be asked whether in the 

 cases where aecidial or uredo conditions are unknown, we are not to expect that they will 

 be hereafter discovered. Such is probably true in most cases, but stUl there are species, as 

 P. malvaeearum, in which it has been supposed that they are absolutely wanting. For the 

 purpose of expressing the presence or absence of the different stages and their relative 

 position, Schroeter divided the genus as follows : 



EupucciNiA. All stages known and all on the same plant. 



Heteeopuccinia. All stages known. Aecidia and spermogonia on one plant, uredo 

 and teleutospores on another plant. 



Hemipuccinia. Only stylospores and teleutospores known, and both occurring simul- 

 taneously on the same plant. 



Puccnsriopsis. Spermogonia, aecidia, and teleutospores known and on different individ- 

 uals of the same species. Uredo unknown. 



