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LICHENS OF baltimore:and vicinity. 
(Abstract of Talk given at Sullivant Moss Society Meeting, Baltimore, 1908.) 
Charles C. Plitt. 
The collection consists of 148 specimens representing 30 genera, contain- 
ing 107 species and their varieties. Nearly all have been collected in the im- 
mediate' vicinity of Baltimore. In the naming of specimens I have depended 
a great deal upon our friend Mr. Merrill who has kindly looked at nearly 
everything I have collected. In the arrangement of specimens I have fol- 
lowed Engler and Prantl as best I could. A glance at the series will show 
that Cladonia alone is represented by 53 specimens, over one-third of the 
whole. This would seem to show that Baltimore is particularly well repre- 
sented in this genus. This is true; but I think that this high showing is due 
to a great extent to our much better knowledge of the Cladonias, and when 
we have a more thorough knowledge of other genera there will also be a 
marked increase in numbers of specimens representing them. To illustrate; 
the 53 specimens of Cladonia represent 26 species and varieties, Parmelia 
will show 14 specimens, representing 12 species; now when we know Parme- 
lia better there will also be a marked increase in its varieties. 
A few words on our most common lichen will possibly be' of interest. 
Which is our most common lichen will be hard to decide. If one limited his 
rambles to country roads alone, it no doubt would be Parmelia Borreri\ if to 
open woods, Cladonia sylvatica ; if along railroads, possibly Baeomyces 
roseus. All three are equally common and can surely not have escaped the 
eye of any tramper in this vicinity. Other more or less common lichens will 
be the following. Should one go along the banks of any of our rocky rivu- 
lets, one is sure to be attracted by the pretty masses of Endocarp 07 i miniatum 
growing on the rocks in the stream sometimes quite submerged. I remem- 
ber the first time that I noticed it, I felt sure it was Hydrotheria for I had 
read that Hydrotheria was the only lichen that lived in that way. but some- 
how or other my plant would not fit the description, and I soon learned my 
brook-loving specimen was Endocarpon. Should one go through the woods 
the stains on the tree trunks will surely attract attention, closer examination 
will possibly reveal Gr aphis with its peculiar heiroglyphic-like markings, or 
Pyrenula with its numerous little elevations as if the bark were blistered, 
both of which are quite common. Another common lichen is Lecidea albo- 
ccerulescens found on nearly every rock in our wooded areas. It belongs to 
the crustose type, and may be recognized at once by the peculiar oily-like 
appearance it gives to the rocks. 
Of the Cladonias our most common is sylvatica , which is so closely 
allied to rangiferina , the true reindeer moss. How I have searched for true 
rangiferina — almost concluding it was not found here — finally, however, I 
fouud a little, but growing E 'so sparingly, as if this climate did not suit it at 
all. Olher common Cladonias are papillaria; didymavax. muscigena; cris- 
tatella \ soon recognized by its beautiful red fruits; pyxidata , with its funnel- 
like stalks ; and verticillata , , 
Umbilicaria , so easily recognized when once seen, is rather rare here; 
my first find of this genus being U. Dillenii. 
