456 
Pole Evans . — The Cereal Rusts. 
Puccinia triticina , Erikss. 
The Brown rust of wheat, now known as P. triticina , Erikss., is probably 
identical with the rust still known in the United States as the ‘ orange- leaf 
rust of wheat, 5 P. rubigo-vera Tritici , originally included under P. rubigo- 
vera , DC. (P. straminis , Fuck. = P. striaeformis , West). Eriksson and 
Henning ( 16 ) first sorted it out under the name P. dispersa forma specialis 
Tritici. 
Five years later Eriksson ( 11 ) showed that the brown rust of wheat 
was a distinct species, which he named P. triticina , Erikss. For he found 
that unlike P. dispersa the teleutospores germinated only after the winter, 
they would not infect Anchnsa through their sporidia. and no infection 
resulted on wheat with the aeddiospores from Anchnsa . 
In the field Uredo triticina is easily distinguished from U redo gram in is 
by its smaller pustules, which usually are found on the leaves only. The 
pustules measure from -3—5 mm. in length and 1— 2 mm. in breadth, and 
are closety crowded together on the leaf surface. Large erumpent pustules 
so characteristic of Uredo graniinis never occur. The spores are round 
to shortly elliptical, 19-20 jx x 24-25 fx, smooth and dirty yellow in colour. 
The Histology of Uredo Triticina. 
When we come to compare the histology of Uredo triticina with that 
of Uredo dispersa we at once find a striking difference between the infection 
organs of these two parasites, as will be seen by comparing Figs. 25-27 
with Figs. 28-30. 
The substomatal vesicle of Uredo triticina is globular in shape, and 
gives origin to a single infecting hypha, from which other hyphae may 
eventually arise. A typical vesicle is shown in Fig. 28. In length this 
vesicle is 21 \x. breadth 12/x, and diameter 1 5 /x. 
In Fig. 30 is shown a transverse section through a stoma, in which 
the appressorium, neck, substomatal vesicle, and infecting hypha with the 
first haustorium is seen. 
The resulting hyphae are very similar to the forms already described 
(with the exception of P. glumarum) and need little mention. 
Puccinia Symphyti-Bromorum , F. Mull. 
Originally the Brown rust of the Bromes was placed together with 
the Brown rust of Rye under the name Puccinia rubigo-vera , DC. 
Eriksson ( 9 ) was the first to separate it off as Puccinia dispersa , Erikss. 
et Henn., forma specialis Bromi. 
Later on he regarded it as a distinct species, Puccinia bromina , 
Erikss. ( 11 ), from the fact that he was unable to infect plants of Rye 
with uredospores from the Bromes. and vice versa to infect Bromes 
with uredospores from the Rye. 
