KERN: BERBERIS VULGARIS IN PENNSYLVANIA 265 
situation it was evident that further investigations were necessary. 
As an example of the way in which the literature may fail to be of 
assistance the case of Lancaster County may be cited. Small & 
Carter’s Flora of Lancaster County (1913) makes no mention 
of the barberry although our work shows that the plant has been 
established there in several places for a considerable time, most 
certainly prior to 1913. 
Next to the literature, and more important in some ways in a 
matter of this sort, are herbaria. Specimens in a herbarium are 
usually accompanied with definite information as to place and 
date of collection, two extremely important points in tracing 
distribution. The two leading herbaria in the state, the one at the 
Academy of Natural Sciences, Philadelphia, and the other at 
Carnegie Museum, Pittsburgh, were consulted and both yielded 
valuable information. More than a dozen other institutional or 
private collections were examined. (Contrary to our expectations 
the Porter specimens were seen at the Academy of Sciences, 
Philadelphia, and not at Lafayette College, Easton. A number 
of years ago, in 1896 or thereabout, fire damaged the herbarium 
of Dr. T. C. Porter, upon which the Flora of Pennsylvania was 
founded, and most of the herbarium was transferred to the 
Philadelphia Academy. 
The most direct aid in checking up localities where barberries 
previously existed, or in going to new localities, came from the 
enthusiastic cooperation of persons in all parts of the state, who 
were interested in plants and had special knowledge concerning 
particular regions. The finding of so large a number of persons 
interested in plants and botanical matters was most gratifying, 
and the contact with them was a most delightful experience as 
well as being our most valuable asset in this piece of work. Alto- 
gether a list of more than 200 names was brought together and 
more than half of these, approximately 116, were consulted either 
by personal interview or through correspondence. Starting with 
the names of those appearing on herbarium specimens and enlarg- 
ing this to include botany and science teachers in various institu- 
tions a sizeable nucleus of botanical enthusiasts was obtained. 
A person interested in the wild and native plants frequently 
knew someone in his own or a neighboring county who was also 
