460 
Pole Evans . — The Cereal Rusts. 
II. P. coronifera , Kleb. With its aecidium on Rhamnus cathartica 
(Aecidium Rhamni , Gmel.). Uredo- and teleutospores on Avena sativa, 
Loliuni perenne , and Festnca elatior. 
There are six specialized forms of P. coronifera : — 
1. P. coronifera Avenae , Erikss. Uredospores from Oats will infect 
only oats, not other grasses. 
2. P. coronifera Lolii , Erikss. Uredospores from Lolium perenne 
will only infect Lolium perenne. 
3. P. coronifera Festucae , Erikss. Uredospores from Festnca elatior , 
but not Avena sativa , Alopecurus pratensis (Erikss.). Holcns mollis and 
FI. lanatns (Kleb.). 
Further experiments are needed in the case of its transference to 
Lolinm perenne , for Eriksson entirely failed to infect this latter, whereas 
Klebahn got a very fair percentage of infections on it. 
4. P . coronifera Hold. Kleb. Uredospores from Holcns mollis and 
H. lanatns infect only these plants. 
5. P. coronifera Alopecnri, Erikss. Uredospores from Alopecnrns 
pratensis infect only Alopecnrns pratensis . 
6. P. coronifera Glyceriae , Erikss. Uredospores from Glyceria 
aqnatica infect only Glyceria aqnatica. 
Uredo coronifera is easily distinguished in the field from Uredo 
graminis on Oats, by its light yellow-coloured pustules. These are of 
smaller size than those of U. graminis and are usually only found on the 
leaf, rarely on the stem. 
The spores are round, yellow, and measure from 20-22 fi in diameter. 
I have evidence to show that the Crowned Rust of Oats does con- 
siderable damage to the Oat crops in the Transvaal. A point of interest 
and one worthy of note is that this rust appears later in the season than 
Uredo graminis. As far as I am aware the aecidium has not been 
definitely shown in this country, but it should be mentioned that MacOwan 
in 1877 collected an aecidium on Rhamnns prinoides in Cape Colony. 
According to Carleton this rust is widely distributed in the States, 
and is heteroecious on Rhamnus lanceolata. 
The Histology of Uredo coronifera Avenae, Erikss. 
The general development of the Fungus agrees in every way with the 
species already described, so that only the more important points will be 
mentioned here. 
The appressorium (only the remains of which are seen in Figs. 38, 39) 
is very similar to that of Uredo graminis , but the attendant substomatal 
vesicle is of very different shape and gives rise at once to two infecting 
hyphae, one from each end of the vesicle. These in turn frequently 
branch dichotomously. 
