ON GRAMINEA 259 
On leaves, culms and glumes of Agropyron caninum, A. 
repens, Brachypodium sylvaticum, Bromus mollis and other 
species, Elymus arenarius, Hordeum vulgare, Secale Cereale; 
. 
’ 
a 
‘ 
a 
‘ 
MW [ 
a b a 
Fig. 197. P. glumarum. a, uredo-sori and b, teleuto-sori, on leaves, nat. 
size; c, teleuto-sori, on glume; d, uredospore; e, teleutospore. 
5 
c 
’ 
‘ 
"J 
5 
4 
. 
‘ 
4 
‘ 
t 
t 
‘ 
Triticum vulgare. It is one of the few species that attack the 
ears, to which it does serious damage. (Fig. 197°) 
This is one of two forms originally included under the collective name 
P. Rubigo-vera DC. ; they can best be distinguished in the uredo-stage. 
In the one, P. glwmarum, the uredo-sori are abundant, clear lemon- or 
sometimes orange-yellow, and stand in long lines, often occupying half the 
leaf-blade ; in the other, P. dispersa and its subordinate forms, they tend 
towards brownish-orange or even chocolate-brown, and are scattered, 
rather thinly and without order, over the whole leaf-surface. Eriksson 
and Henning first proved in 1896 what had been long surmised, that they 
are quite distinct. P. glumarum has no known ecidial form, and has 
been divided into five biological races (see p. 67). It is common in certain 
districts of England and is called the Spring Rust on account of its 
early appearance, and Yellow Rust on account of its bright colour, which 
varies from sulphur- to pale cadmium-yellow. The lines of the uredo-sori 
may be as much as 7 cm. long, chiefly on the upper face of the leaf; they 
can be found all the year round on suitable leaves, and are frequently 
abundant on Wheat as early as the beginning of May. The teleutospores 
germinate as soon as they are mature; the basidium is yellow until 
the basidiospores are formed, not colourless as in P. dispersa. 
On Hordeum murinum there is recorded a form, P. Hordet Fckl., 
which has smaller yellow sori, arranged less evidently in lines; this may 
belong to P. gluwmazum but has not yet been found in Britain. It is 
probably not identical with P. simplex (q. v.). 
DisTRIBUTION : Europe, Egypt, North America, Japan. 
17—2 
