This website is still a work in progress, but currently serves as a supplement for the systematics side of Biology 414. It will supplement class lectures on family identification and field recognition in the course.
The phylogenetic trees shown below and on linked pages represent relationships between angiosperm lineages. Clicking on parts of these trees will take you directly to more information on the group (where provided). Text within major groups is arranged taxonomically by order and then family. In addition, photographic examples of representatives are listed beneath families (including many families that won't be covered in detail in this course).
The text provided herein is meant to serve as a study guide for family recognition in the course. Even when modifiers such as "usually" or "generally" aren't used, the familial characteristics listed are rarely universal within a family. The characteristics indicated are the states most likely to be encountered in eastern North America and Pennsylvania and often are less applicable elsewhere, particularly in the tropics. Family identification is rarely a decision that can be made based on one characteristic; thus, it is always important to rely on a suite of features, because exeptions always exist.
Decisions on which families will be covered in class are subject to change and are based on availability in the field during the course, ecological and economical importance, recognizability, and how interesting they are likely to be to students in the course. Taxonomic treatment of the families in this website follows no rules or prior treatments, but is based on the following criteria: is the family well-supported as a monophyletic group?, is the family recognizable to students in a three week field course?, and how easy is it to teach the family as currently recognized? Of course, no difficult taxonomic decision can satisfy everyone. Traditional taxonomy based on morphology is often easier to learn and creates groups that are readily recognizable to beginning students. However, these groups are sometimes totally artificial or paraphyletic, and a systematic view based on molecular data can provide interesting insight into the evolutionary history of a lineage and associated traits. In cases where taxonomic changes based on molecular evidence are not extremely well-supported (such as combination of Aceraceae, Hippocastaneaceae, and Sapindaceae), traditional circumscription is often used, even though it is likely incorrect. In other cases, such as in the Liliaceae, the family is certainly not monophyletic as included, but until all of the relationships within the group are resolved, it is again instructionally easier to adhere to traditional taxonomy. By contrast, inclusion of Monotropaceae within Ericaceae is very well-supported, and the floral structure of these plants is obviously Ericaceous, despite the fact that the lineage is distinctively non-photosynthetic. Students will be expected to recognize families for field identification based on the treatment in this website, but will also be required to know some background information on taxonomically-debated groups and their likely evolutionary relationships as discussed in class.
Some references consulted during assembly of the information contained here include:
APG (Angiosperm Phylogeny Group). 1998. An Ordinal Classification for the Families of Flowering Plants." Annals of the Missouri Botanical Garden. 85: 531-553.
APG (Angiosperm Phylogeny Group). 2003. An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG II." Bot. J. Linnean Soc. 141: 399-436.
APG Angiosperm Phylogeny Group III (2009), An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: AGP III", Botanical Journal of the Linnean Society 161:105-21.
Cronquist. 1981. An Integrated System of Classification of Flowering Plants. New York Botanical Garden.
Gleason and Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. New York Botanical Garden.
Heywood. Flowering Plants of the World. 1978. Mayflower Books.
Judd, W. S., C. S. Campbell, E. A. Kellogg, and P. F. Stevens. 2002. Plant Systematics: A Phylogenetic Approach, Second Edition. Sinauer Associates, Inc.
Rhoads and Block. 2007. (2nd ed.) The Plants of Pennsylvania. University of Pennsylvania Press.
Rhoads and Klein. 1993. The Vascular Flora of Pennsylvania: Annotated Checklist and Atlas. American Philosophical Society.
Stevens, P.F. 2002. Angiosperm Phylogeny Website; 27 March 2010. http://www.mobot.org/MOBOT/research/APweb/.
While references were consulted for constructing the phylogenetic trees pictured herein, the end product is a conglomeration of multiple references, data from my lab, and my own observations. Thus, due credit for phylogenies should be given to the references above, but blame for any error should fall to me! This website was developed by Joel McNeal when he was a doctoral student in the Biology Department at Penn State University. Updates since Spring 2004 by Claude dePamphilis. All photographs ©2004 Joel McNeal, unless otherwise indicated.
Any corrections for this website and any questions about Biol 414 at Penn State University or the photographs should be e-mailed to Claude dePamphilis
This index provides a quick link to plant families that contain images and/or descriptions on this site. Families are listed in alphabetical order. Those with an asterisk are covered in Biology 414; those in parentheses are included herein under other families.
Click on the scientific or common names listed below to skip directly to the family to which each species belongs. Once you are at the family, you may have to scroll down to reach the species photographs you are looking for.