Systematics and Evolution of the Ericales

The plant order Ericales contains ca. 8000 species of flowering plants distributed in 22 families. The order contains a number of economically important edible plants, including tea (Camellia sinensis), kiwi (Actinidia), persimmon (Diospyros), Brazil nut (Bertholettia excelsa), star-apple (Chrysophyllum cainito), and blueberries and cranberries (Vaccinium), as well as popular ornamental plants such as azaleas and rhododendrons (Rhododendron), primroses (Primula), Impatiens, Erica, Phlox, and Camellia. The order comprises mainly trees and terrestrial shrubs, but some are vines, perennials, or epiphytes. Other families include carnivorous species (e.g., pitcher-plants of Sarraceniaceae) or parasites (e.g., Mitrastemon, Sarcodes).

My research on Ericales employs the study of morphological and molecular data to document species diversity and endemism in the group and understand how it evolved. I ask questions about how many species are in particular subgroups or clades (species discovery and taxonomy), how they should be classified, how they have dispersed from one area of the globe to another (biogeography), and how their features have adapted to their environment. For groups that have a fossil record, I incorporate paleobotanical data to estimate when lineages diverged to better understand how ancient climates changed over the course of the Cenozoic Period (Age of Mammals). Much of my research utilizes phylogenetic trees, that is, estimates of species and higher-order relatedness, for inferring evolution. My scientific program is highly collaborative, involving colleagues at BRIT, at other U.S. institutions, and internationally.

The families that I study most intensively are the silverbell (Styracaceae), sweetleaf (Symplocaceae), and heath or blueberry (Ericaceae) families. With colleagues, I have discovered over 40 species from among these groups, and also described a new genus (Perkinsiodendron). Recent work has includes a comprehensive phylogenetic study of the wintergreen tribe of the heath family (Gaultherieae), in which I and my colleagues inferred the evolution of fruit color variation linked to geographic location and elevation. Current focus extends to the genus Vaccinium (blueberries and cranberries, especially in North America, Polynesia, and Southeast Asia.