in the Bromes and their Brown Rust . 239 
whence its name is derived, while the other, P. simplex , Kcke., 
has been separated off from the old P. rubigo-vera , D. C., as 
peculiar to Hordeum. 
In 1897, in fact, the three hitherto accepted species of grain- 
rusts had been broken up as follows : — 
(1) P. graminis , Pers., into P. graminis and P. Phlei - 
pratensis. 
(2) P. rubigo-vera , D. C., into P. glumarum, Er. and Henn., 
P. dispersa , Er. and Henn., and the variety P '. simplex, Kcke. 
(3) P. coronata , Corda, into P. coronifera , Kleb, P. coronata y 
Kleb, and an eighth form on Calamagrostis and Melica as yet 
unnamed. 
Moreover, each of these species possessed several form- 
species, or specialized races, morphologically indistinguishable 
but physiologically confined to certain hosts h 
Since I am here concerned only with the Uredo-forms of 
the species given, the following comparison must be supple- 
mented by reference to the authorities quoted for information 
as to the teleutospores, &c. 
I may, however, add the morphological definitions of the 
species, so far as the Uredo-forms are concerned. 
Puccinia graminis > Pers. The Black Rust of cereals. 
The Uredo pustules occur as large elongated spots, 2-3 mm. 
in length and sometimes confluent, especially on the sheaths, 
and may then be very long, up to 10 mm. or more. They are 
yellow-brown — brown-ochre, or sienna — in colour, and bear 
uredospores which are of a dirty yellow hue, and echinulate, 
and measure about 17-40 x 14-22 jot. 
Puccinia glumarum , Er. and Henn. The Yellow Rust of 
wheat. 
The Uredo pustules, or sori, are o-i-i mm. long and 
o-3~o-4 mm. broad. In linear series confluent in long streaks 
at the leaf-apex, and may be there grouped into disease- 
flecks as much as 70 mm. long. They are apt to be more 
1 See Eriksson, Ber. d. D. Bot. Ges., 1897, Bd. xv, p. 183, and Bot. Gaz., 1898, 
vol. xxv, p. 28, for details. 
