ON GRAMINE.*: 



265 



On leaves and culms of Hordeum vulgare and other species 

 of Hordeum. Teleutospores, August, September. (Fig. 202.) 



The Dwarf Brown Rust of Barley, distinguished by the fact that it 

 hears few two-celled teleutospores, but very numerous mesospores, which 

 are variable and asymmetrical, slightly thickened at the apex (4 — 6/x), 

 measuring 25 — 45 x 16 — lip. It is to be found in the uredo-stage all the 

 year round. The teleutospores germinate in spring ; Klebahn tried to 

 infect, with their basidiospores, the same forty-two species which he 

 tested with P. tritivina, but equally in vain. 



P. simplex. Teleutospores. 



P. simplex may be worthy of being regarded as a distinct species ; it 

 presents a little more difference from the other forms of P. dispersa than 

 they do from one another. The sori of both kinds are amphigenous and 

 more minute and punctiform (except on the culms), and the uredospores 

 are of a brighter yellow. On Hordeum distichum I have found sori of 

 P. simplex on the leaves, and with them those of P. graminis on the culms. 



It will be noticed that all the last five races are without 

 any known secidium ; it follows, apparently, that they must 

 maintain themselves by their uredospores, but one might 

 venture to suggest that future, unexpected, discoveries will 

 throw light upon this obscure matter. Eriksson and Klebahn 

 have both proved, by numerous infection experiments, that 

 these races or subspecies of P. dispersa are .all biologically 

 distinct; with few, and doubtful, exceptions none of them can 

 be transferred from its own to the other hosts. 



There are other forms of Brown Rust of which little is 

 known. The aecidium on Echium vtdgare mentioned by Plow- 

 right (Ured. p. 168) may belong to one of these ; this plant was 

 one of the forty-two previously mentioned, tested by Klebahn. 



I have also some specimens of uredospores on Aira fiexuosa 

 and A. caespitosa sent by Mr T. B. Roe from Scarborough: those 



