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A PRELIMINARY LIST OF THE ERYSIPHEiE OF MONTANA. 
By F. W. Anderson. 
Whatever effect the abundance or scarcity of rain, or the degree of at¬ 
mospheric and terrestrial humidity from other sources, may have upon 
the propagation of Peronosporece and Uredinece , it is certain that the 
Erysiphece , in Montana at least, are not very materially affected by even 
an unusual lack of such moisture. Montana this year, in company 
with many other Western States, has suffered from an almost unprece¬ 
dented drought. Yet, while all ordinary vegetation languishes, and 
while Uredinece , usually so abundant everywhere, are hard to find, the 
Erysiphece have appeared on most of their usual hosts in fair abun¬ 
dance. 
In looking over the published Lists of Erysipliece from various 
States, or in comparing herbarium specimens of a given species on the 
same or different hosts from a number of States, one is struck at once 
by the wide range of variation in the specific characteristics of that 
species. This is especially noticeable where a species has a wide geo¬ 
graphical distribution and a great number of hosts belonging to differ¬ 
ent families. In fact, it is frequently a difficult task to assign some of 
these forms which may be intermediate between two related and vari- 
able species. For example: Within the range of the two common spe¬ 
cies of the genus Erysiphe — E. communis and E.cichoracearum —we find 
at times the most perplexing variations of all kinds, from the form and 
disposition of the mycelium, up to the number and size of the asci and 
spores. One is sometimes tempted to think that they are but one u run¬ 
ning” species, or else that some day an intermediate specific rank 
will be erected to embrace the more radical of the intermediate varia¬ 
tions from the two types. One or the other alternative must sooner or 
later be adopted in order to find a resting place for some of the Rocky 
Mountain forms which are clearly neither the one nor the other, but 
which are certainly intermediate. There are species in other genera 
also which would be made easier to deal with by a similar modification. 
I hope in a future paper to discuss our peculiar Rocky Mountain forms 
more fully, and with this object in view it may not be out of place at 
this time to ask botanists of the Rocky Mountain region to send me 
specimens of the species and forms common to their several localities. 
I should be happy to send them good specimens from Montana in ex¬ 
change. 
This short preliminary list is published with the hope that other res¬ 
ident or traveling botanists in Montana may be stimulated to a more 
earnest study of this important family. The species have been collected 
by myself on the hosts and in the localities given except as otherwise 
indicated. Spring Hill is on the Idaho border at the southwest, west 
of the main divide. The Valley of the Teton is near the British line 
