PREFACE. 



Dr. Porter began the collecting and study of the plants of 

 Pennsylvania about the year 1836 and continued both, essen- 

 tially without interruption, until his death in 1901. He per- 

 sonally explored nearly every part of the State ; but the infor- 

 mation thus obtained represents only a portion of the data 

 recorded on the following pages. His connection with several 

 colleges in Pennsylvania for a period of over fifty consecutive 

 years gave him a wide acquaintance with intelligent persons 

 throughout the State, and those interested in plants, more espe- 

 cially the students who came under his influence, did all in their 

 power to enlarge his collection of specimens, so that his State 

 Flora might ultimately be essentially perfect. Thus, through 

 personal exploration and the enthusiastic cooperation of others 

 for a period of over sixty 3'ears, the herbarium upon which this 

 Flora is based contains plants brought together from all of the 

 sixt5'^-one counties of Pennsylvania. 



Professor Porter's ambition to make his list of Pennsylvania 

 plants complete led him to defer printing it from time to time. 

 So averse was he to giving his work to the public before the 

 list of native plants was complete, that when death overtook 

 him in his eightieth year, the work which he had endeavored 

 to make perfect remained unpublished. However, the manu- 

 script was nearly completed many years ago and was left with 

 most of the more recent discoveries properly recorded. Being 

 so earnestly interested in the botany of Pennsylvania and de- 

 siring that others might ultimately have the benefit of his 

 studies, he made provision for its publication in his will. 



After the author's death, at the request of his executor. Pro- 

 fessor S. A. Martin, I consented to edit the manuscript. I had 

 long been intimately acquainted with Dr. Porter and with his 

 work, and during frequent interviews, the flora of Pennsylva- 

 nia and the form in which it should be published was often the 

 main subject of conversation and discussion. Being thoroughly 

 acquainted with the author's ideas, I can confidently say he 

 would heartily subscribe to everything on the following pages. 



J. K. Small. 



New York, August 15, 1903. 



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