CAS CONNECT 2017

34 Doctoral student discovers unidentified plant species found only in a corner of Texas W hile doing research at the Missouri Botanical Garden in St. Louis for her dissertation, Oklahoma State University graduate student Angela McDonnell came across a mystery. A botanist there showed her a pressed, dried specimen of a milkweed vine plant from Texas unlike any of its closest relatives. The plant hadn’t been described or named since first being collected in 1903. “Dr. [Peter] Stevens [a botanist at the Missouri Botanical Garden who specializes in milkweed vines] thought it was the species Matelea decipiens , but he wasn’t positive,” says McDonnell, a doctoral student in OSU’s Department of Plant Biology, Ecology and Evolution. “He asked me to look at it, and it definitely wasn’t Matelea decipiens .” McDonnell began a search to identify the mystery milkweed. That led to new plant species and, as is the scientific custom for the discoverer, she gave the plant its scientific name, Matelea hirtelliflora , and its common name, the hairy-faced spiny pod. “She cast a broad net over this group of plants that she specializes in, and that led her to an inkling that this could be a new species,” says Mark Fishbein, an OSU professor and McDonnell’s advisor. Confirming that the plant was indeed something new became a side project as she worked to complete her Ph.D. “I study plants that belong to a lineage of around 500 species of milkweed vines called Gonolobinae . Within that lineage, I have focused on a smaller group of around 20 close relatives in the genus Chthamalia that occur in Oklahoma, Texas and throughout Mexico,” McDonnell says. “I use genomic informa- tion to estimate relationships among different species that allow me to better understand how different traits, like growth form, fruit shape and flower shape, have evolved over time.” How does a botanist study plants? McDonnell utilized dried, pressed plant specimens held in museum collections, or herbaria, and borrowed samples from institutions across the U.S., including the botanical garden in Missouri, the University of Texas in Austin, Whi le Angela McDonnel l ( left) worked on her Ph.D. under advisor Dr. Mark Fishbein (r ight), she discovered a new species of mi lkweed – the hai ry-faced spiny pod.