68 CROWN RUST 



each of these tonus would not infect the other hosts, so far as 

 they were tried. It is doubtful if the two last forms are dis- 

 tinct, as they were not tested sufficiently. 



A more complicated case is seen in P. coronata Corda, the 

 Crown Rust. Not only is this divided by Eriksson and Klebahn 

 into two sub-species, P. coronata and P. Lolii (= coronifera), 

 but each of these is still further sub-divided by them into 

 biological races. 



In P. coronata (aecidium on Rhamnus Frangula) they are: 



1. f. Calauiagrostidis — on C. lanceolata etc. (also on Phalaris) 



2. f. Phaloridis — on /'. arundinacea (also on Calamagrostis) 



3. f. Agrostidis — on .1. rn/garis, A. alba, A. stolonifera 



4. f. Hold — on //. lanatus, H. mollis 



5. f. Agropyri — on A. repens. 



The state of P. coronata which occurs on Dactylis has not 

 yet been assigned to any of these forms. The last two of them 

 seem doubtful and may not belong to P. coronata, and the first 

 two of them may be identical, since each seems able to extend 

 at times to the other host. 



In P. Lolii, the Crown Rust of Oat (aecidium on Ph. cathar- 

 ticus), they are : 



1. f. A venae — on A. sativa, A. fatua 



2. f. Lolii — on L. perenne (perhaps also on Festuca elatior) 



3. f. Festucae — on F. elatior, F. gigantea 



4. f. Hold — on H. lanatus, H. mollis 



0. f. Alopecuri — on A. pratensis etc. 



6. f. Glyceriae — on G. aquatica. 



To which of these the form of P. Lolii on Arrhena- 

 therum should be assigned seems to be undecided. There are 

 also Crown Rusts, of which little is known, on Melica nutans 

 and Sesleria coerulea. 



Later {Arkiv for Botanik, 1908, vol. viii) Eriksson revises 

 his previous conclusions in regard to P. Lolii as follows, making 

 eight races : 



1. f. A venae — on Avena 



■1. f. Alopecuri — on Al. pratensis, etc. (sometimes on Av. sativa) 



3. f. Festucae — on F. elatior, F. gigantea 



4. f. Lolii — on Loliurn perenne and other species (also on F. elatior) 



