This work, by three Professors Emeritus from the University of Pennsylvania and Penn State University, summarizes some (presently) 50 years of work on the flora of Pennsylvania, last published (in toto) in 1903 by Porter.
This work, by three Professors Emeritus from the University of Pennsylvania and Penn State University, summarizes some (presently) 50 years of work on the flora of Pennsylvania, last published (in toto) in 1903 by Porter.