UROMYCES ON GRASSES 69 
or 
f. Glyceriae—on G. aquatica 
6. f. Agropyri—on A. repens 
f. Epigaei—on Calamagrostis epigeios (also, but rarely, on Avena 
sativa) 
8. f. Holei—on Holcus lanatus. 
a 
To these Miihlenthaler (1910) adds a ninth form, on several 
species of Bromus. These results agree pretty well with those 
of Klebahn, but not with those of Carleton. According to the 
latter, the only host of P. Loli in nature, in the United States, 
is Avena sativa: but in artificial cultures it can be foisted on 
other species because of the unnatural conditions, especially 
on account of the employment of very young and non-resistant 
plants. In any case, however, there is a general agreement 
that the form of P. Lolit on Avena sativa cannot be transferred 
to Wheat, Barley, or Rye. In fact, with the exceptions 
mentioned, it was found by all experimenters more or less in 
all these cases, that attempts made to transfer the fungus from 
the host of one “special form” to those of the others were 
unsuccessful from some unknown cause. 
The state of things in regard to the two common Uromyces 
species, found upon Grasses, is more perplexing. There is no 
agreement whatsoever between the various authors who have 
experimented upon them. The latest results are, perhaps, the 
following : 
Krieg (1909) divides Uromyces Dactylidis into two biological 
races or “ formee speciales ” : 
l. f£ sp. with ecidium on Ranunculus bulbosus, R. repens 
2. f. sp. with ecidium on several non-British species of Ranunculus. 
Juel (Svensk Bot. Tidskr. ii. 169, 1908) divides Uromyces 
Poae into nine biological races, of which the following seven 
may be British: 
. sp. Ficariae-nemoralis 
. sp. Ficariae-trivialis 
. sp. Ficariae-pratensis 
. Sp. repentis-nemoralis (also on R. bulbosus) 
. Sp. repentis-trivialis (also on Poa annua) 
. Sp. repentis-pratensis 
. Sp. auricomi-pratensis. 
BT Se Ore ge NS 
bor oP rh rh ph fh 
