self portrait

Susan Swensen Witherup

Professor, Biology
Phone: 607-274-3511
Office: 256 Center for Natural Sciences
Specialty: Botany/Plant Systematics and Evolution
Office Hours: Spring 2024

CNS 256:

  • Tuesdays 9-10am
  • Thursdays 4-5:30 pm
  • or by appointment


B.A. Grinnell College, Biology

M.S. University of Tennessee, Botany

Ph.D. University of Tennessee, Plant Physiology & Genetics


My research addresses questions about the evolutionary history of plants. To answer such questions, I and my research students analyze plant DNA. Molecular systematics is the use of DNA (and other molecules) to reconstruct phylogenies (our best guesses of evolutionary history). We have used molecular systematics to study the evolutionary relationships among different species of plants in the order Cucurbitales  (cucumbers, squashes, begonias, and a few other smaller plant families). We are also using DNA at the level of populations to study small-scale evolution within a species. Population genetics is the use of genetic information to characterize the variation that exists in populations.

The questions that most intrigue me are evolutionary ones. For example, how did Hillebrandia (a begonia) come to exist in Hawaii and nowhere else? How did bacterial symbioses in plant roots evolve? How do plants and their parasites co-evolve?  More recently, my students and I have begun to look at the question of how species evolve on islands. We are characterizing the genetic variation in the inkberry (Scaevola plumieri) in Puerto Rico using microsatellites as a way to understand how this native species might be impacted by a closely related invasive species (Scaevola taccada).

If you are interested in joining me in my research, click the link below:

Student-Faculty Research Options