Whole Plant Evolution


The Edwards Lab is in the Department of Ecology and Evolutionary Biology at Brown University.

We are botanists and evolutionary biologists. We are inspired by the diverse ways in which plants look and act, and want to understand how this diversity has evolved. Phylogeny is at the heart of everything we do, and we are committed to the development of model lineages for studying evolution. We also always try to think as integratively as possible, and keep the whole organism in mind as we dive into minutia. Currently we are focused on a couple of different lineages and questions.

  • Portullugo

    The "Portullugo" is a clade of ~2200 species that live in a wide variety of habitats and are found on every continent, though they have a penchant for deserts and the high alpine (lucky us). The lineage includes well known groups such as the cacti, and less famous but equally wonderful plants like the Molluginaceae, the purslanes, lewisias, and the Didiereaceae.

  • C4 and CAM evolutionary trajectories

    We are especially interested in how C4 and CAM photosynthesis, two fairly complicated plant adaptations to low CO2, hot temperatures, and drought, have evolved so many times (~100s), mostly over the past 15 or so million years. We have worked on the C4 problem in grasses and are currently focusing our attention on C4 and CAM origins in the Portullugo, a lineage that holds a suprising number of both C4 and CAM plants.

  • Viburnum

    Viburnum is a clade of ~165 species of woody shrubs and trees common in northern hemisphere forests, but they are also found in tropical Asia and montane forests throughout Central and South America. We collaborate closely with the Donoghue Lab on all things Viburnum, and are especially interested in using this lineage to study the evolution of leaf form and function, and in tropical-temperate biome transitions.


Edwards lab members, past and present.

Erika Edwards

Principal Investigator

My CV is available here.

Zachary Lewis


evolutionary morphology and development; organogenesis

Eric Goolsby


phylogenetic comparative methods, phylogenomics, plant ecophysiology

Laura Garrison

Graduate Student

phenology, climate change, Viburnum, plant diversity. My CV is available here.

Lilly Hancock

Graduate Student

evolution of CAM photosynthesis; Australian Montiaceae. My CV is available here.

Morgan Moeglein

Graduate Student

Genetic basis of ecologically relevant traits; leaf shape evolution in Viburnum. My CV is available here.

Elissa Johnson

Post-bac research associate

Morphology, diversity, evolution, and natural history of all living things. Histology, imaging, scientific illustration.

Haley Carter


phylogenetics, Viburnum, plant chemistry

Andrew Pisaturo


biogeography, ecology, hiking


Research Assistant

botanical illustration; mosses


Research Assistant

flora of Mt. Kinabalu; bananas

Lab Alums:

Abigail Moore, post-doc (2013-2016)

Jurriaan de Vos, post-doc (2013-2015)

David Chatelet, post-doc (2010-2015)

Radika Bhaskar, post-doc (2011-2014)

Pascal-Antoine Christin, post-doc (2010-2012)

Monica Arakaki, post-doc (2009-2012)

Matt Ogburn, phD student (2007-2012)

Eric Kelosa-Kenyon, undergrad (2013-2015)

Regan Lichtenberg, undergrad (2013-2015)

Arisa Lohmeier, undergrad (2012-2014)

Elizabeth Spriggs, undergrad and research technician (2008-2012)

Asya Rahlin, undergrad (2011-2012)

Alejandro Brambila, undergrad (2011-2012)

Sam Schmerler, undergrad (2008-2011)

Anne Williard, undergrad (2008-2009)

Cassidy Metcalf, undergrad (2007-2008)

Kaya Schmandt, research tech (2008-2010)

Teaching and outreach

Bio 43: The Evolution of Plant Diversity

This course has several, interrelated objectives. First, it serves as an introduction to the science of phylogenetics, providing an overview of both the theory and methodology involved in constructing phylogenetic trees, and how to use trees to study character and organismal evolution. For our second objective, we put this new framework to immediate use by using phylogeny to explore and illustrate 400 million years of land plant evolution. Bio43 examines major trends in plant evolution from functional, ecological, and biogeographical perspectives. Students will leave the class with a basic understanding of 1) phylogenetic theory and methods of studying character evolution, 2) plant anatomy and morphology, 3) evolutionary relationships among the major land plant clades (with emphasis on the flowering plants), and 4) major evolutionary trends that have significantly shaped the diversity of plant life that we see today. The third and most important objective is to instill in students the ability to look at any biological problem through the lens of "phylogeny-colored glasses"- a powerful way to examine the complexity of life that surrounds (and includes) us.

2015 syllabus

Bio 150: Plant Ecological Physiology

The primary aim of Bio 150 is to examine the role of the environment in shaping the anatomical, physiological, and ecological diversity of vascular plants. Lectures provide an overview of plant-environment interactions, focusing on anatomical and physiological adaptations of leaves, stems, and roots to different habitats. A comparative, phylogenetic approach is emphasized. This is a hybrid lecture/seminar course, where classes consist of both chalkboard lectures as well as discussions of articles from the primary literature. In addition, BIO 150 is designed to be a hands-on course, and lectures are viewed mostly as supplements to the semester-long greenhouse project that provides students with first-hand experience in measuring and interpreting plant functional traits. Students work on a set of group projects designed to test long-standing assumptions about the evolution and adaptive nature of certain plant traits. Projects will differ from year to year, but will be chosen by the professor based on outstanding questions in the current literature. Students will leave the class with a solid foundation both in plant functional ecology and in applying a phylogenetic comparative approach to studies of organismal biology. Furthermore, they will gather first hand experience in data collection, experimental design, data analysis, and the presentation of a scientific study.

2013 syllabus

CreatureCast: Branching Out

Our plant-y contributions to the Dunn Lab's creaturecast website. Animations about weird and beautiful plant life, (mostly) created by Brown undergrads enrolled in Bio43. All animations created under a creative commons license and freely available to use in any educational setting.


Forrestel EJ, MJ Donoghue, EJ Edwards, W Jetz, JCO du Toit, MD Smith. 2017. Different clades and traits yield similar grassland functional responses. Proceedings of the National Academy of Sciences 114: 705-710. pdf

Barish S, M Arakaki, EJ Edwards, MJ Donoghue, WL Clement. 2016. Characterization of 16 microsatellite markers for the Oreinotinus clade of Viburnum (Adoxaceae). Applications in Plant Sciences 4: 1600103. pdf

Thulin M, AJ Moore, H El-Seedi, A Larsson, PA Christin, EJ Edwards. 2016. Phylogeny and generic delimitation in Molluginaceae, new pigment data in Caryophyllales, and the new family Corbichoniaceae. Taxon 65: 775-793. pdf

Edwards EJ, EL Spriggs, D Chatelet, MJ Donoghue. 2016. Unpacking a century old mystery: winter buds and the latitudinal gradient in leaf form. American Journal of Botany 103: 975-978. pdf

Scoffoni C, D Chatelet, J Pasquet-Kok, M Rawls, MJ Donoghue, EJ Edwards, L Sack. 2016. Hydraulic basis for the evolution of photosynthetic productivity. Nature Plants 2: 16072. pdf

Bhaskar R, S Porder, P Balvanera, EJ Edwards. 2016. Ecological and evolutionary variation in community nitrogen use traits during tropical dry forest secondary succession. Ecology 97: 1194-1206. pdf

Holtum JAC, L Hancock, EJ Edwards, M Crisp, D Crayn, R Sage, K Winter. 2016. Australia lacks stem succulents but is it depauperate in plants with Crassulacean Acid Metabolism (CAM)? Current Opinion in Plant Biology 31: 109-117. pdf

Ogburn RM, EJ Edwards. 2015. Life history lability underlies rapid climate niche evolution in the angiosperm clade Montiaceae. Molecular Phylogenetics and Evolution 92: 181-192. pdf

Yang X, JC Cushman, AM Borland, EJ Edwards, and 47 others. 2015. A roadmap for research on crassulacean acid metabolism (CAM) to enhance sustainable food and bioenergy production in a hotter, drier world. New Phytologist 207: 491-504. pdf

Edwards EJ, JM de Vos, MJ Donoghue. 2015. Brief Communications Arising: Doubtful pathways to cold tolerance in plants. Nature 521, doi:10.1038/nature14393. pdf

Spriggs EA, WL Clement, PW Sweeney, S Madrinan, EJ Edwards, MJ Donoghue. 2015. Temperate radiations and dying embers of a tropical past: the diversification of Viburnum. New Phytologist 207: 340-354. pdf

Christin PA, M Arakaki, CP Osborne, EJ Edwards. 2015. Genetic enablers underlying the clustered evolutionary origins of C4 photosynthesis in angiosperms. Molecular Biology and Evolution 32: 846-858. pdf

Donoghue MJ, EJ Edwards. 2014. Biome shifts and niche evolution in plants. Annual Review of Ecology, Evolution, and Systematics 45: 547-572. pdf

Gao L, EJ Edwards, Y Zeng, Y Huang. 2014. Major evolutionary trends in hydrogen isotope fractionation of vascular plant leaf waxes. PLoS ONE 9(11): e112610. pdf

Edwards EJ. 2014. The inevitability of C4 photosynthesis. eLife 3:e03702. pdf

Howison M, F Zapata, EJ Edwards, CW Dunn. 2014. Bayesian genome assembly and assessment by markov chain monte carlo sampling. PLoS ONE 9(6): e99497. pdf

Clement WL, M Arakaki, PW Sweeney, EJ Edwards, MJ Donoghue. 2014. A chloroplast tree for Viburnum and its implications for phylogenetic classification and character evolution. American Journal of Botany 101: 1029-1049. pdf

Christin PA, M Arakaki, CP Osborne, A Brautigam, RF Sage, JM Hibberd, S Kelly, S Covshoff, GKS Wong, L Hancock, EJ Edwards. 2014. Shared origins of a key enzyme during the evolution of C4 and CAM metabolism. Journal of Experimental Botany 65: 3609-3621.pdf

Hancock L, EJ Edwards. 2014. Phylogeny and the inference of evolutionary trajectories. Journal of Experimental Botany 65: 3491-3498. pdf

Spriggs EL, PA Christin, EJ Edwards. 2014. C4 photosynthesis promoted species diversification during the Miocene grassland expansion. PLoS ONE 9(5):e97722. pdf

Edwards EJ, DS Chatelet, L Sack, MJ Donoghue. 2014. Leaf life span and the leaf economic spectrum in the context of whole plant architecture. Journal of Ecology 102: 328-336. pdf

Christin PA, E Spriggs, CP Osborne, CAE Stromberg, N Salamin, EJ Edwards. 2014. Molecular dating, evolutionary rates, and the age of the grasses. Systematic Biology 63: 153-165. pdf

Still CJ, S Pau, EJ Edwards. 2014. Land surface skin temperature captures thermal environments of C3 and C4 grasses. Global Ecology and Biogeography 23: 286-296. pdf

Christin PA, SF Boxall, R Gregory, EJ Edwards, J Hartwell, CP Osborne. 2013. Parallel recruitment of multiple genes into C4 photosynthesis. Genome Biology and Evolution 5: 2174-2187. pdf

Chatelet DS, WL Clement, L Sack, MJ Donoghue, EJ Edwards. 2013. The evolution of photosynthetic anatomy in Viburnum (Adoxaceae). International Journal of Plant Sciences 174: 1277-1291.pdf

Edwards EJ, MJ Donoghue. 2013. Is it easy to move and easy to evolve? Evolutionary accessibility and adaptation. Journal of Experimental Botany 64: 4047-4052. pdf

Ogburn RM, EJ Edwards. 2013. Repeated origin of three-dimensional leaf venation releases constraints on the evolution of succulence in plants. Current Biology 23: 722-726. pdf

Christin, PA, CP Osborne, DS Chatelet, JT Columbus, G Besnard, TR Hodkinson, LM Garrison, MS Vorontsova, EJ Edwards. 2013. Anatomical enablers and the evolution of C4 photosynthesis in grasses. Proceedings of the National Academy of Sciences USA 110: 1381-1386. pdf

Pau S, EJ Edwards, CS Still. 2013. Improving our understanding of environmental controls on the distribution of C3 and C4 grasses. Global Change Biology 19: 184-196. pdf

Christin PA, MJ Wallace, H Clayton, EJ Edwards, RT Furbank, PW Hattersley, RF Sage, TD Macfarlane, M Ludwig. 2012. Multiple photosynthetic transitions, polyploidy, and lateral gene transfer in the grass subtribe Neurachninae. Journal of Experimental Botany 63: 6297-6308. pdf

Schmerler S, W Clement, J Beaulieu, D Chatelet, L Sack, MJ Donoghue, EJ Edwards. 2012. Evolution of leaf form correlates with temperate/tropical transitions in Viburnum. Proceedings of the Royal Society of London B: Biological Sciences 279: 3905-3913. pdf

Liu H, EJ Edwards, R Freckleton, CP Osborne. 2012. Phylogenetic niche conservatism in C4 grasses. Oecologia 170: 835-845. pdf

Ogburn RM, EJ Edwards. 2012. Quantifying succulence: a rapid, physiologically meaningful measure of plant water storage. Plant, Cell and Environment 35: 1533-1542. pdf

Feild T, EJ Edwards. 2012. Celebrating giant steps toward a synthetic history of angiosperm evolution. Special issue of International Journal of Plant Sciences 173: 599-560. pdf

Edwards EJ, RM Ogburn. 2012. Angiosperm responses to a low CO2 world: CAM and C4 photosynthesis as parallel evolutionary trajectories. Special issue of International Journal of Plant Sciences 173: 724-733. pdf

Christin PA, EJ Edwards, G Besnard, SF Boxall, R Gregory, EA Kellogg, J Hartwell, CP Osborne. 2012. Adaptive evolution of C4 photosynthesis through recurrent lateral gene transfer. Current Biology 22: 445-449. pdf

Christin PA, G Besnard, EJ Edwards, N Salamin. 2012. Effect of genetic convergence on phylogenetic inference. Molecular Phylogenetics and Evolution 62: 921-927. pdf

Grass Phylogeny Working Group II. 2012. New grass phylogeny resolves deep evolutionary relationships and discovers C4 origins. New Phytologist 193: 304-312. pdf

Taylor SH, PJ Franks, SP Hulme, E Spriggs, PA Christin, EJ Edwards, FI Woodward, CP Osborne. 2012. Photosynthetic pathway and ecologial adaptation explain stomatal trait diversity amongst grasses. New Phytologist 193: 387-396. pdf

Sage RF, PA Christin, EJ Edwards. 2011. C4 plant lineages of planet Earth. Special issue of Journal of Experimental Botany 62: 3155-3169. pdf

Christin, PA, CP Osborne, RF Sage, M Arakaki, EJ Edwards. 2011. C4 eudicots are not younger than C4 monocots. Special issue of Journal of Experimental Botany 62: 3171-3181. pdf

Arakaki M, PA Christin, A Lendel, R Nyffeler, U Eggli, RM Ogburn, E Spriggs, M Moore, EJ Edwards. 2011. Recent and contemporaneous radiations of the worlds succulent plant lineages. Proceedings of the National Academy of Sciences USA 108: 8379-8384. pdf

Christin PA, T Sage, EJ Edwards, RM Ogburn, R Khoshravish, RF Sage. 2011. Complex evolutionary transitions and the significance of C3-C4 intermediate forms of photosynthesis in Molluginaceae. Evolution 65: 643-660. pdf

Ogburn RM, EJ Edwards. 2010. The ecological water-use strategies of succulent plants. invited review, Advances in Botanical Research 55: 179-255. pdf

Davis CC, EJ Edwards, MJ Donoghue. 2010. A clade's eye view of global climate change. in M. A. Bell, D. J. Futuyma, W. F. Eanes, and J. S. Levinton, eds. Evolution since Darwin: the first 150 years. pp. 623-627. Sinauer, Sunderland, Massachusetts. pdf

Edwards EJ*, CO Osborne*, CAE Stromberg*, SA Smith and the C4 Grasses Consortium. 2010. The origins of C4 grasslands: integrating evolutionary and ecosystem science. Science 328: 587-591. pdf Supplemental material. *indicates equal authorship

Edwards EJ, SA Smith. 2010. Phylogenetic analyses reveal the shady history of C4 grasses. Proceedings of the National Academy of Sciences USA 107: 2532-2537. pdf Supplemental material

Haberle RC, A Dang, T Lee, C Penaflor, H Cortes-Burns, A Oestreich, L Raubeson, N Cellinese, EJ Edwards, ST Kim, WMM Eddie, RK Jansen. 2009. Taxonomic and biogeographic implications of a phylogenetic analysis of the Campanulaceae based on three chloroplast genes. Taxon 58: 715-734.

Cellinese N, SA Smith, EJ Edwards, ST Kim, RC Haberle, MJ Donoghue. 2009. Historical biogeography of the endemic Campanulaceae of Crete. Journal of Biogeography 36: 1253-1269. pdf

Edwards EJ. 2009. The Great Cacti: Ethnobotany and Biogeography, by David Yetman. Quarterly Review of Biology 83: 00-00.

Ogburn RM and EJ Edwards. 2009. Anatomical variation in the closest relatives of cacti: trait lability and evolutionary innovation. American Journal of Botany 96: 391-408. pdf

Nyffeler R, U Eggli, RM Ogburn, EJ Edwards. 2008. Variations on a theme: repeated evolution of succulent life forms in the Portulacineae. invited paper, Haseltonia 14: 26-36. pdf

Butterworth CA, EJ Edwards. 2008. Investigating Pereskia and the earliest divergences in Cactaceae. invited paper, Haseltonia 14: 46-53. pdf

Edwards EJ, CJ Still. 2008. Climate, phylogeny and the ecological distribution of C4 grasses. Ecology Letters 11: 266-276. pdf

Edwards EJ, CJ Still, MJ Donoghue. 2007. The relevance of phylogeny to studies of global climate change. Trends in Ecology and Evolution 22: 243-249. pdf

Edwards EJ. 2006. Correlated evolution of stem and leaf hydraulic traits in Pereskia (Cactaceae). New Phytologist 172: 479-489.pdf

Edwards EJ, MJ Donoghue. 2006. Pereskia and the origin of the cactus life form. American Naturalist 167: 777-793. pdf

Edwards EJ, M Diaz. 2006. Ecological physiology of Pereskia guamacho, a cactus with leaves. Plant Cell and Environment 29: 247-256 pdf

Riedel SM, EH Epstein, DA Walker, DL Richardson, MP Calef, EJ Edwards, A Moody. 2005. Spatial and temporal heterogeneity of vegetation properties among four tundra plant communities at Ivotuk, Alaska, USA. Arctic, Antarctic, and Alpine Research 37: 25-33. pdf

Edwards EJ, R Nyffeler, MJ Donoghue. 2005. Basal cactus phylogeny: implications of Pereskia paraphyly for the transition to the cactus life form. American Journal of Botany 92 (7): 1177-1188. pdf

Brodribb TJ, NM Holbrook, EJ Edwards, MV Gutierrez. 2003. Relations between stomatal closure, leaf turgor and xylem vulnerability in eight tropical dry forest trees. Plant Cell and Environment 26: 443-450. pdf

Walker DA, HE Epstein, JG Jia, A Balsar, CD Copass, EJ Edwards, WA Gould, J Hollingsworth, J Knudson, HA Maier, A Moody, MK Reynolds. 2003. Phytomass, LAI and NDVI in northern Alaska: relationships to summer warmth, soil pH, plant functional types, and extrapolation to the circumpolar Arctic. Journal of Geophysical Research 108 (D2): 8169 doi:10.1029/2001JD000986.

Bell CD, EJ Edwards, ST Kim, MJ Donoghue. 2001. Dipsacales phylogeny based on chloroplast DNA sequences. Harvard Papers in Botany 6: 481-499. pdf