NORTH AMERICAN SPECIES OF PERI- 
DERMIUM ON PINE 1 
Joseph Charles Arthur and Frank Dunn Kern 
Nearly eight years ago the writers published an article in the 
Bulletin of the Torrey Botanical Club 2 treating of the species of 
Peridermium then known in North America. Since that time 
much information has accumulated to supplement what was there 
said and to correct some errors. That article w r as founded upon 
meager material for the most part, but all then available, yet it 
served an important purpose in stimulating observation and in 
directing attention to the less known forms. 
It is now proposed to review that portion of the previous 
article which related to the forms of Peridermium occurring upon 
the leaves and bark of various species of pine, and to leave the 
remainder of the article for possible future notice. In thus re- 
stricting the w r ork it will be feasible to show some advances that 
have been made in the last eight years, to discuss the difficulties 
encountered in limitation and identification of species, and to set 
forth the more conspicuous problems for the future. To do this 
much for the pine-inhabiting species will require as much space 
as can well be granted for a single article, although other genera 
of gymnospermous hosts bear species of Peridermium in equal 
need of similar presentation. 
The first discussion of the American pine-inhabiting forms was 
by Underwood and Earle 3 in 1896, who ably presented the subject 
as known at that time. Only three species were recognized from 
the eastern United States: Peridermium acicolum and P. orientate 
both on leaves and P. cerebrum on bark. Two species not seen 
by the authors had been described from western United States : 
P. filamentosum and P. Harknessii, both on bark. A species from 
1 Read before the Botanical Society of America, Atlanta meeting, De- 
cember 31, 1913. 
2 Volume 33, pp. 403-438. 1906. 
3 Underwood, L. M., & Earle, F. S. : Notes on the pine-inhabiting species 
of Peridermium. Bull. Torrey Club 23: 400-405. 1896. 
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