W O R L D    P L A N T S

Flowering Plants of Pennsylvania

By Michael Hassler, Bruchsal, Germany - Technical realization by Bernd Schmitt

In cooperation with Botanical Garden of the Karlsruhe Institute of Technology

Disclaimer: The author of the website does not take over responsibility for the correct determination of species based on the information or photos contained on this website, and any impact resulting from this, e.g. in the consumption of species shown in the picture for medical purposes.


Flora of Pennsylvania and New Jersey


A pictorial and taxonomic database



by Michael Hassler (Bruchsal, Germany)






Pennsylvania and New Jersey have a rich flora with about 3750 recorded species in total, of them about 2200 native. Although a modern flora of Pennsylvania has been published recently (Rhoads & Block, 2nd ed., 2007), as well as a distribution atlas (Rhoads & Klein, 1993) and a website with county data there is no comprehensive, reasonably complete picture collection on the internet or elsewhere available.


While working for two years (mid 2004 to mid 2006) in State College in the chemical industry, I have, with the help of numerous collaborators and with lots of subsequent field trips during business visits until 2012, assembled a collection of more than 2700 species in digital pictures, which represent about three quarters of the total amount. Because of my location in central Pennsylvania , the flora of this part of the state is represented much better. Some European neophytes and adventives are represented by pictures taken in Europe.


The picture size for the database (900 x 1150 pixels maximum) was chosen fairly high, in order to maximize the use of the pictures for identification. Most pictures are between 100 and 300 kbyte in size. We hope that this is acceptable to most internet users with broadband access.


In 2012 a major upgrade was done. Now our website uses a complete checklist and synonymy as provided by the USDA PLANTS database, and the distribution records of BONAP. The New Jersey data have been included, boosting the total from 2800 to 3580 species, and the pictured total from 2100 to 2710 species.

The species have been listed in the database together with some basic information (synonymy, general distribution in Pennsylvania and New Jersey, county records of central Pennsylvania, red list data, habitats, flowering time, etc.), even if no picture is available yet. We hope that other photographers will contribute and donate pictures, in order to create a most complete reference picture collection for the Pennsylvania and New Jersey flora.


There are undoubtedly quite a few initial errors in this database, therefore we would welcome suggestions and corrections.


Michael Hassler, February 2013



Thanks to


While photographing for this collection, I had the help of numerous experts for the PA and NJ flora, who gave me detailed tips how to find plants and joined me for excursions.


Special thanks go to Harry Henderson (State College) and Prof. Larry Klotz (Shippensburg). Without their generous and long-time help this database could not have been as complete as it is today. Harry Henderson could also use data he got over many years from the – too early - deceased George Beatty, probably one of the leading experts for the state flora. Both Harry Henderson and Larry Klotz helped with the determination of a great many difficult specimens, especially numerous sheets of Carex.


Much help came also from:

Norm Deno (State College) and the amazing and beautiful wildflower collection in his garden

Tim Draudte

Frank Fee ( State College )

William “Rocky” Gleason (Middletown)

Bob Gruver (State College)

Steve Johnson (Sunbury)

Roger Latham (Rose Valley)

Daniel Laughlin (Flagstaff)

Clark Shiffer (State College)

Prof. Kim Steiner, Kathleen Reeder and Tim Phelps (Arboretum of Penn State University)

Eugene Zielinski (Augusta)


For picture contributions we are grateful to:

Aaron Carlson (Menomonie, WI) (www.flickr.com/people/59003943@N00/)
Alan Cressler (www.flickr.com/photos/alan_cressler/)
Alexander Mrkvicka (Wien)
Allen Crawford (www.flickr.com/photos/34822101@N08/)
Andreas Kleinsteuber (Karlsruhe)
Bernd Haisch (†) (Stutensee)
Brad Wilson (Atlanta, GA) (www.flickr.com/photos/frogdr/)
Carl Luer (Sarasota, FL)
Carol Lund (Clemson)
Corey Raimond (Wisconsin) (www.flickr.com/photos/28511931@N07/)
Dan Mullen (Wisconsin) (www.flickr.com/photos/8583446@N05/)
Dieter Hassler (Kraichtal)
Eric Hunt (Little Rock) (www.flickr.com/photos/ericinsf/)
Ernst Horak (Wien)
Eugene Zielinski (Augusta)
Exner (Botanik im Bild, Wien)
Gerd-Uwe Kresken (Schleswig-Holstein)
Günther Blaich (Mannheim)
Hans Schön (Botanik im Bild, Wien)
Harald Geier
Harry Henderson (State College, PA)
Harry Rose (Australia) (www.flickr.com/photos/73840284@N04/)
J. C. Schou (www.biopix.dk)
Jeffrey Pippen (www.duke.edu/~jspippen/nature.htm)
Jenny Dressler (Costa Rica)
Joachim Rheinheimer (Ludwigshafen)
Joaquín Ramírez López (www.naturalezadeandalucia.blogspot.com)
John Hagstrom (OH) (www.flickr.com/photos/37738527@N06/)
Julia Kruse (Bayreuth)
Jürgen Alberti (Bad Schönborn)
Karlheinz Knoch (Bruchsal-Büchenau)
Keir Morse (California) (www.keiriosity.com)
Kerry Wixted (Annapolis, MD) (http://www.flickr.com/photos/kwixted0/)
Layla Dishman (Texas) (www.flickr.com/photos/layladishman/)
Martin Schulze-Dieckhoff
Martin Sommerfeld (Karlsruhe)
Matt Lavin (Montana State University) (www.flickr.com/photos/plant_diversity/)
Melanie Schori (Athens, OH) (www.flickr.com/photos/7791651@N07/)
Mike Turner (www.flickr.com/photos/61962421@N05/)
Peter Woods (Erie, PA) (www.flickr.com/photos/peteandnoewoods/) (Images courtesy of Western Pennsylvania Conservancy)
Sonnia Hill (Texas) (www.flickr.com/photos/carthamus/)
Steve Johnson (PA)
Svein Erik Larsen (Spain) (www.flickr.com/people/sveineriklarsen/)
Thomas Brune
Thomas Meyer (Günzburg)
Tyler W. Smith (Ottawa) (www.flickr.com/photos/carex/)
Ulrich Lorimer (New York) (www.flickr.com/photos/53817483@N00/)
Volker Kummer (Leipzig)
and others (see credits under the various pictures).





Even after 300 years of research, the taxonomy of the Pennsylvania flora is still somewhat in flux. New latin names and combinations are published on a regular basis. Especially the new volumes of the Flora of North America are very important.

We have used a latin taxonomy which is derived from the checklists used in the USDA PLANTS database, the BONAP lists and the Flora of North America. In some cases the newest available taxonomy was included.


We have therefore listed the synonyms quite detailed and made them searchable, in order to simplify the process of finding a plant.


English trivial names are notoriously fluctuating and unreliable – in some cases every field guide has different ones. We have mostly used the names used in the USDA PLANTS database.




Photographic equipment


Most of the pictures have been taken between 2004 and 2012, using a Sony DSC F828 digital camera, which has a marvelous macro function and lens never really surpassed by newer camera models.

Some older pictures, especially of European aliens and neophytes, have been taken in Europe in the years before, using older equipment like Sony DSC F717 and Sony DSC S75.


A minor percentage, mostly macro photos with high magnification, were taken with Canon D10 and D20 cameras, using a 100 mm Canon macro lens. The author uses this equipment mostly for insect and other animal photography, whereever short focus times are critical.


The pictures were deliberately taken in a relatively dark mode, which avoids overexposure to white and yellow colors (still a major problem in digital photography) and gives more natural colors. Still, the differences between various cameras and flash/non-flash modes are huge.






Basic literature:


Rhoads, A. F. & Klein, W. M. (1993): Vascular Flora of Pennsylvania: Annotated Checklist and Atlas (Memoirs of the American Philosophical Society). 636 p. [out of print]


Rhoads, A. F. & Block, T. A. (2000): The Plants of Pennsylvania: An Illustrated Manual. - 1061 p. University of Pennsylvania Press. [out of print, new edition in preparation]


Rhoads, A. F. & Block, T. A. (2004): Trees of Pennsylvania: A Complete Reference Guide. - 407 p. University of Pennsylvania Press.



The most recommended field guides:


Newcomb, L. (1989): Newcombs Wildflower Guide. 13th ed., 490 p.


Clemants, S. & Gracie, C. (2006): Wildflowers in the Field and Forest: A Field Guide to the Northeastern United States (Jeffrey Glassberg Field Guide Series). Oxford University Press, 480 p.


Petrides, G. A. (1998): A Field Guide to Eastern Trees. (Peterson Field Guides). 2nd ed., 441 p.





Pennsylvania Flora Project website


Flora of North America


Flora of North America website


PLANTS database for all of North America


Connecticut Wildflower Society (picture gallery)


Wildflowers of Western Pennsylvania


Delaware Wildflowers