Botany Staff & Associates


Tanya Livshultz

Dr. Tatyana Livshultz
Assistant Curator of Botany

Interests: Systematics of Apocynaceae
Ph.D. Cornell University 2003
Every multi-cellular organism begins as a single cell that then undergoes a coordinated process of development to reach its mature form. Evolution has continuously reshaped this process to produce the diversity of plant and animal species we see around us today. The fundamental question I’m interested in is how developmental programs are modified through evolutionary time to produce novel and complex forms. My focus is on the Apocynaceae, the milkweed and dogbane family, a group of ca. 4000 species of flowering plants. The milkweed flower is among the most complex, comparable only to that of the orchid in the modification of its form and the precision of its pollination mechanism. Flowers of dogbanes are simpler, although there are also species with flowers of intermediate complexity. I’m using methods including evolutionary tree reconstruction and comparative development to understand how the complex milkweed flower evolved from the simpler flower of a dogbane-like ancestor.
I’m also studying the evolution and species diversity of the genus Dischidia, a group of about 80 species from Southeast Asia that have evolved a symbiotic relationship with ants including some remarkable chemical and morphological modifications that function in this relationship. Species of Dischidia have ant-attractive seeds, inducing the ants to collect them, and some also modified leaves that function as ant houses.
As curator of the PH herbarium, one of my priorities is to develop databases that allow researchers to easily access information from herbarium specimens to track changes in plant distributions, flowering times, and associations. These data are fundamental to helping us understand the unprecedented global change that we are experiencing today. As one of the oldest herbaria in North America, with specimens dating to the 18th century, the Academy’s collection represents a uniquely long record of plants over time. The information contained in these specimens is currently difficult to use since it is distributed among a million plus individual samples. Assembling this information into a database where it can be easily accessed and queried will help reveal how our environment has been changing over the past 300 years.

Rick McCourt

Dr. Richard McCourt
Curator of Botany

Interests: Algal systematics, historical botany
Ph.D. University of Arizona.
I do research on the evolution and systematics of green algae, specifically a group known as charophyte algae. These are the green algae that are the closest living relatives of land plants and include some well-known algae such as Spirogyra and stoneworts. I'm interested in understanding the phylogeny of these algae-that is, their evolutionary relationships with other algae and with land plants. I'm interested to know what were the evolutionary events that allowed the descendants of charophyte algae to emerge from their habitats in freshwater ponds onto land. For details, see the Academy news website and my Personal Research website.
I also work on the Lewis and Clark Herbarium at the Academy, and with Earle E. Spamer have co-authored a Special Publication CD-ROM and other publications on the Lewis and Clark Herbarium. I have worked at the Academy since 1997. Before that I was an Associate Professor at DePaul University in Chicago, where I taught ecology, evolution, and introductory biology.

woman with long blond hair in flower shirt in front of plant background

Dr. Chelsea R. Smith
Collection Manager

For herbarium inquiries, please email:

Ernie Schuyler

Dr. Alfred E. (Ernie) Schuyler
Curator Emeritus

Interests: Historic American botanical collections; historic botanical literature and art.
Ph.D. University of Michigan.
My present research interests are in the (1) systematics and ecology of rare plant species, (2) relationships between plant diversity and environmental quality, and (3) history of botanical exploration in North America. I also teach university, college, and adult education courses in plant systematics, ecology, and environmental issues.

Ms. Elana Benamy
Curatorial Assistant

My academic background is in invertebrate paleontology and museum studies (MS in Geology and Certificate in Museum Studies, both from the University of Delaware). I have continued my education in natural history collections care and conservation through short courses and workshops, many of which were sponsored by the Society for the Preservation of Natural History Collections (SPNHC, pronounced “spinach”). I have been an active member of SPNHC for many years and have served as a Council Member-at-Large on its Board, and was secretary of the Society for many years.
After working for many years as Collection Manager for the Invertebrate Paleontology collection here at the Academy, I have been involved with projects including the Malacology Department’s Indo-Pacific molluscan database, Entomology’s type specimen database and their Titian Peale Butterfly and Moth Collection’s Save America’s Treasures grant involving databasing and imaging the Peale boxes as they were being conserved (see I also worked on the Patrick Center’s orphan collections project, finding, cleaning, sorting, rehousing and databasing field collections involving aquatic organisms from algae to fish (with a variety of invertebrate phyla in between). I am currently working on the Botany Department’s LAPI (Latin American Plant Initiative) project databasing and scanning images of the type specimens in the Academy’s Herbarium.


Dr. Jordan K. Teisher
Research Associate

Interests: Systematics of grasses (Poaceae), in particular subfamilies Arundinoideae and Micrairoideae.
Ph.D. Washington University in St. Louis 2016
B.S. Moravian College 2009

I study phylogenetic relationships and evolution in two poorly-studied grass subfamilies: Arundinoideae and Micrairoideae (family Poaceae). These subfamilies contain morphologically and ecologically diverse species that have been difficult to classify because of their lack of clear synapomorphies and their frequently remote localities. To better understand these taxa, I use a combination of molecular phylogenetics, histology, scanning electron microscopy, and herbarium taxonomy. Resolution of phylogenetic relationships within the Arundinoideae and Micrairoideae allow investigation of a wide range of evolutionary phenomena, including the evolution of floral traits important in dispersal and burial, the role of polyploidy and hybridization in the invasion of novel habitats, and the effect of acquisition of the C-4 photosynthetic pathway on subsequent diversification of a clade.”

Guy Nesom
Research Associate

Ph.D. - University of North Carolina, Chapel Hill
B.A. - Davidson College, Davidson, North Carolina

As a plant taxonomist, my goals are to bring to light the diversity of species and their geographical distributions, to fit them into a system of nomenclature, to provide means for their identification, and (information-permitting) to provide hypotheses about their evolutionary relationships. I've used various techniques but herbarium study and field work underlie most of my studies. It's a joy to become familiar with all these plants (love the sidewalk "weeds"!), it's astounding how much remains remains to be known about species diversity even in long-explored regions, and it's always a thrill to encounter a previously unrecognized and unnamed species.

Through mid 2021, I'm author or coauthor of nearly 550 journal articles, books, and research reviews. These include studies on plants in 30+ plant families and descriptions of 260+ new species (not counting "new combinations" etc.).

For the Flora of North America project, I've contributed taxonomic treatments of genera to the 3 volumes of Asteraceae and family-level treatments of Cucurbitaceae, Garryaceae, Melastomataceae, Oleaceae, Oxalidaceae, Phrymaceae, Rhamnaceae, and Verbenaceae, as well as various genera of Apiaceae, Araliaceae, Fabaceae, Lamiaceae, Rosaceae, Sapindaceae, and Scrophulariaceae. Outside of FNA research, I've centered on the taxonomy of plants of the southeastern and western USA, as well as a broader reach into Mexico and other parts of the world. Most of this involves American Asteraceae but I've described 37 new genera of tribe Astereae (3100+ species worldwide) from Africa, Asia, and Australia, as well as from North America. In 2020, I revised the subtribal classification of Astereae.

The online journal Phytoneuron (; 2010 to the present) publishes taxonomic studies of the North American and Central American flora, without charge to authors and with completely open access. I'm editor/publisher, without compensation.

My wife and I moved from Texas to Philadelphia in 2019 for a cooler clime and to be near our daughter, who lives here. Herbarium PH was not a minor factor in the consideration.

Dr. Alina Freire-Fierro
Research Associate

Interests: Systematics of Neotropical Polygalaceae, Monnina in particular; Andean flora
Ph.D. Drexel University 2015
My research is focused on Neotropical Polygalaceae, in particular Monnina, as well as Ecuadorian Saxifragaceae s.l. and neotropical floristics. During my studies and career, I have done extensive fieldwork in the Andean region of Ecuador, as well as in the Campos rupestres of Brazil. I have also done field trips to Bolivia and Costa Rica. My morphological research, and molecular studies suggest that Monnina is a monophyletic group with a high variability in habit (herbs to small trees) and fruit morphology (drupes to samaras). The papilionaceous flowers are very similar, except for two species endemic to northeastern Brazil that exhibit flowers very different.
Besides the revision of Monnina, I have been working with floristic treatments of Polygalaceae from Bolivia, Antioquia (Colombia), and the Southern Cone. I have recently started working at the Academy. Before that, I was a Research Specialist at the Missouri Botanical Garden, where I am now a Research Associate.
Throughout my career I have met many colleagues from Latin American and, in order to facilitate communication within the community, I have created and administer the discussion group Anuncios Botanicos.

Dr. Walter F. Bien
Research Associate

Interests: Plant community ecology, flora of the New Jersey Pine Barrens, rare plant conservation, synecology of Sphagnum.
My botanical interest focuses on plant community ecology with special interest on the role that fire plays in facilitating habitat for disturbance-dependent species. Students in my lab are currently researching: fire effects on seed banking and dispersal mechanisms in Rhynchospora knieskernii; effect of anthropogenic disturbance on pollinator success in Gentiana autumnalis, and systematics of Mesoamerican Monnina (Polygalaceae).

Dr. Timothy Block
Research Associate

Interests: Flora of Pennsylvania Project, GIS.
My research interests are in the flora of Pennsylvania and in GIS mapping of plant distribution.

Dr. Walt Cressler
Research Associate

Interests: Paleobotany and paleoecology of the Late Devonian Period; Development of terrestrial ecosystems.
My research interests focus on the evolution and ecology of plants and continental ecosystems of the Late Devonian Period, the time of the earliest forests and of the earliest seed plants. I work with Academy vertebrate paleontologist Ted Daeschler and others on characterizing the habitats of the earliest tetrapods which also date from this period.

Dr. David Hewitt
Research Associate


Interests: urban and suburban ecology (especially in eastern North America), ascomycete ecology, history of botany.
My research includes and has included field biology (plants, fungi, soils), history of botany (Lewis David von Schweinitz) microbiology (algae, fungi), paleontology, and cell/molecular/developmental biology. My fieldwork has primarily been in eastern North America and Europe, generally in pretty well inhabited areas (urban and suburban areas).

James C. Lendemer
Research Associate

Interests: Floristics and taxonomy of lichens and lichenicolous (specifically Usnea and Lepraria); typification.
My research focuses on the taxonomy and floristics of lichenized and Lichenicolous fungi, particularly those that occur in eastern North America. Primarily I am interested in documenting the biodiversity of Appalachian Mountains of eastern North America and the coastal plain of the southeastern United States. However I my interested have led me to conduct studies elsewhere in eastern North America, including the limestone barrens of the Northern Peninsula of the Island of Newfoundland (Canada), southern New Jersey, and the state of Pennsylvania. In recent years I have also become interested in taxonomy and evolution of the genus Lepraria. Using a multifaceted approach involving extensive field work to observe the species in nature and better understand their specific ecological role/requirements, molecular techniques, micro- and macro- morphological characters (particularly Scanning Electron Microscopy), chemical data, and culture data my colleagues and I hope to arrive at a better understanding this highly successful genus of lichenized fungi that has evolved to reproduce entirely asexually. I have also recently begun my PhD studies at The New York Botanical Garden which will involve a revision of the genus Lecania in North America using an approach similar to that which my colleagues and I have developed for Lepraria. In addition to my lichenological studies I edit and publish the primarily online lichenological journal Opuscula Philolichenum, am an associate editor of Bartonia (The Journal of the Philadelphia Botanical Club), and chair of the Bryophyte and Lichen Technical Commission (BLTC) of the Pennsylvania Biological Survey (PABS).

Dr. Ben LePage
Research Associate
215-841-5572 (phone)
215-776-5588 (mobile)

Interests: Plant Evolution, wetlands, plant/habitat conservation
I want to better understand the evolution of our modern boreal and temperate forests through integration of the complex interactions between biotic and abiotic systems across multiple spatial and temporal scales.
Plant evolutionary studies have been traditionally compartmentalized and neglect to address the interrelationships, processes and feedbacks that cross traditional scientific boundaries. By integrating botanical, genetic, geological, paleontological and geochemical tools, my research identifies key drivers, processes, interactions and feedback mechanisms that regulate plant evolution.

Dr. James Macklin
Research Associate

Interests: Hawthorns (Crataegus, Rosaceae) and collections and informatics.
My taxonomic research continues to focus on species level variability influenced by complex breeding systems in one of the most economically important families of plants, the Rosaceae (Rose Family), especially Rubus (Raspberries and Blackberries) and Crataegus (Hawthorns). I have always been interested in historical botany and especially how botanists have influenced today’s nomenclatural nightmares.
My other growing area of interest is in biodiversity informatics. I am involved in several projects that involve data capture through taking high-resolution images of specimens, capturing their label and ancillary data in custom databases, and serving this information through secure, interactive websites.

Christine Manville
Research Associate

Interests: Bryophytes of Pennsylvania
My primary botanical interest is in the distribution of bryophytes (i.e., mosses, liverworts and hornworts) and lichens. I have been associated with the Academy's department of botany since 1984. I have worked on other museum collections, as diverse as vascular plants and molluscs. My primary emphasis is on the distribution of bryophytes and lichens in Pennsylvania. Previous research included work on peat bogs and lake sediments for pollen and subfossil remains. These bits of evidence can be assembled to provide detailed information on vegetation history. I am also interested in the history of botanical work in Pennsylvania.

Elizabeth P. McLean
Research Associate

I became fascinated by plants. I studied three years at the Barnes Arboretum under Jack Fogg. Participation in the activities of the Philadelphia Botany Club (President 1979-1981), and guidance from Ernie Schuyler increased my understanding of plant material. I annotated the type collection in the herbarium at the Academy under James Mears (1978 -1983). I have focused on plants collected by John Bartram, and co-authored a paper with Dr. Schuyler "The Versatile Bartrams and Their Botanical Legacy" to be published by the American Philosophical Society. My most recent project for the Academy was a field trip with Ernie Schuyler in 1997 to Montana to do on-site research for the Academy's Lewis and Clark exhibit at he Philadelphia Flower Show in 1998.

Dr. Lucinda McDade
Research Associate

Interests: Vascular plants, Acanthaceae systematics.
My research has three interrelated centers of focus. First, I seek to understand the evolutionary history of plants by unraveling their phylogenetic relationships. I have studied the large (>4000 species), worldwide (but mostly tropical and subtropical) plant family Acanthaceae for nearly 25 years, both at the species level and at higher levels. Second, phylogenies permit us to understand the evolution of specific traits of plants or of interactions between plants and other organisms. I have a long-standing interest in plant reproductive biology, in particular the evolution of pollinator relationships and breeding systems in members of the Acanthaceae. I also have a collaborative project studying the evolution of floral scent in multiple lineages in which hawkmoth pollination has been gained and lost. Third, hybridization is widely understood among botanists to be an important evolutionary mode but current phylogenetic methods cannot discover hybridization. I have studied the impact of hybridization on phylogenetics from both theoretical and empirical perspectives. My research has field, lab and herbarium components. Since my graduate student days, I've done a great deal of fieldwork in the New World tropics. More recently, I've begun to work in Africa as well; I spent three very productive months in South Africa in 2000.

Dr. Gerry Moore
Research Associate

Interests: Floristics of the northeastern United States, especially the New York Metropolitan region and southern New Jersey; taxonomy of Cyperaceae, especially Rhynchospora, and Rosaceae, especially Rubus; botanical nomenclature.
My floristic interests focus on the local region. I am especially interested in documenting change, such as the spread of non-native invasive species and decline of native species. My current taxonomic interests focus on revisional work on Rhynchospora sect. Paniculatae found in the neotropics and developing a better understanding of our local Rubus species. I am active in botanical nomenclature, being a former nomenclature co-editor for Taxon and former member of the Committee for Spermatophyta. I am also the incoming editor of Bartonia, the journal of the Philadelphia Botanical Club.

Dr. Robert F. C. Naczi
Research Associate

Interests: Flora of eastern North America, systematics of Cyperaceae, systematics of Sarraceniaceae.
My floristics research centers on revising the Manual of Vascular Plants of Northeastern United States and Adjacent Canada (Gleason & Cronquist 1991). The goals of this project are to produce a new Manual that reflects all of the advances of botanical science during the last two decades, and to create an accompanying online Flora. My systematics research concerns revision of groups within the sedge genera Carex and Rhynchospora (Cyperaceae) and the Western Hemisphere Pitcher Plants (Sarraceniaceae). The groups on which I focus are those whose classifications are poorly resolved and for which novel data sets show promise for resolving these problems.

Dr. Terry O’Brien
Research Associate

Interests: Systematics and ecology of bryophytes, especially mosses.

Dr. Ann Rhoads
Research Associate
215-247-5777 ext. 134

Interests: Floristic Botany of Pennsylvania, plant conservation.
My research interests are focused on the floristic botany of Pennsylvania. I want to document the natural vegetation of the state and better understand historical and contemporary influences that have shaped the patterns of plant distribution we see today.

William H. Roberts
Research Associate

My research interests focus primarily on the flora of the West Coast of Newfoundland, Labrador and the Canadian arctic; Cyperaceae; the history of systematic botany; and botanical references in ancient Greek and Latin literaturein including Homer, Theocritus and Virgil.

Dr. Benjamin Torke
Research Associate

Interests: Systematics, biogeography, and evolutionary diversification of Neotropical trees, with emphasis on the genus Swartzia (Leguminosae).
My current research is motivated by an interest in the tremendously high levels of species diversity that characterize tree communities in lowland Neotropical rainforests. A major goal is to understand the historical, ecological, and evolutionary mechanisms that underlie the diversifications of species-rich clades of Neotropical trees. To this end, I am deeply involved in a long-term international collaborative effort to build a variety of biological datasets for the genus Swartzia (Leguminosae), which has about 200 species distributed throughout the lowland Neotropics, particularly in rainforests. Extensive fieldwork in Neotropical countries and a growing collection database provide the raw data for systematic and evolutionary studies. My doctoral research produced the first molecular phylogeny for Swartzia and the only comprehensive biogeographic analysis of the genus. Research at the Academy focuses on particular clades of closely related species of Swartzia and utilizes molecular phylogenetic and phylogeographic approaches to reconstruct the timing and evolutionary histories of population divergences and speciation events. Future efforts will incorporate GIS-based analyses to examine broad scale environmental correlates of genetic divergence, speciation, and cladogenesis and will focus on the role of breeding systems and chromosomal evolution in speciation. Ultimately, I hope to make all of these studies and datasets broadly available such that Swartzia can be used as model system for the study of Neotropical tree diversification.
One of the most exciting parts of my work entails the examination of new herbarium collections from remote parts of the distribution of Swartzia. These specimens have often brought to light the existence of species new to science. As such, I am always happy to receive Swartzia specimen loans or gifts for determination.

Dr. Erin Tripp
Research Associate

I study the evolution of a diverse and geographically widespread plant family,Acanthaceae (~4,000 species). For my dissertation research, I use molecular phylogenetics to investigate species relationships and morphological evolution in the large genus Ruellia (~300 species) and associated tribe Ruellieae (1,000 species). Well-supported and well-sampled phylogenies are among the best tools that allow us to understand how and why some of the most interesting plant traits and plant symbioses have evolved over time. In Acanthaceae, this includes relationships to pollinators and floral (or vegetative) traits that affect such relationships.
I have three other primary research interests. I have studied and continue to have interest in the flora of the tepuis in western Guyana. On a more local level, I am involved in studies on vegetation dynamics in the Great Smoky Mountains and lichen diversity in the mountains and coastal plain of North Carolina.

Dr. Rachel Wilson
Research Associate

Interests: Biochemistry of germination, algal evolution.
My research interests are in the physiology and biochemistry of plant development. I have studied the hormonal regulation of embryogenesis in bean (Phaseolus) and the roles of specific enzymes in the mobilization of stored protein during barley grain germination. More recently I have become interested in the evolution of land plants which has led to a focus on spore germination in one group of charophycean algae (Zygnematales).