NSFDEB-NERC: Subtribal classification and generic delimitation among Eastern Hemisphere ironweeds (Vernonieae, Compositae).

The biodiversity crisis is among the most urgent global threats facing humanity in the 21st century. With nearly half a million plant species on Earth, understanding their diversity is a key priority. However, there are too many plant species and not enough trained taxonomists to study, describe and distribute information about them.

This is especially problematic for large plant families such as the sunflower family (Compositae), which includes more than 30,000 species and nearly 2,000 genera. One of the hyper-diverse plant groups within this family includes approximately 1,500 species of “ironweeds” (Vernonieae), which has proven so challenging for botanists that it is often referred to as the “evil tribe”.

Until recently, most species of “ironweeds” (>1,000) were placed into a single, broadly defined genus, Vernonia. However, this genus has been reduced to include only 21 species restricted to the Americas. In the Eastern Hemisphere alone, Vernonieae is represented by more than 700 species and more than one third of these remain in the genus Vernonia, awaiting placement in a different genus.

This project will support critical sampling of DNA and morphological characters from ironweeds in the Eastern Hemisphere based on field and herbarium collections. These genetic and morphological data will clarify taxonomic boundaries in the tribe and form the basis of comparative studies to understand evolutionary relationships among species in this diverse and economically important group of plants.

Data collected as part of this work will be added to the newly established Global Compositae Database (GCD), a public, online taxonomic resource. Results of this work will be broadly distributed through the GCD, and new, integrative taxonomic tools will be made available. This project will also provide broad support to the global community of Compositae specialists through the GCD and inspire and train the next generation of plant taxonomists through workshops, tutorials, public lectures, and videos.

Training will be provided to a diverse and international community of students at various stages of their education (from K-12 to graduate school), professionals (e.g., collections managers and curators, postdocs, and faculty), and the public.

Outcomes from this project will have a significant impact on how we describe and communicate about diversity in a large and historically challenging group of plants (Vernonieae), which in turn is part of the most species-rich plant family on Earth (Compositae). Botanists who specialize in the taxonomy of Vernonieae have struggled to understand the characters that can help differentiate among the more than 700 species in this tribe that occur in the Eastern Hemisphere.

Field work will be based in five countries (namely Democratic Republic of the Congo, Madagascar, Mozambique, South Africa, and Thailand) and collections will be studied from four herbaria, which hold the largest historical collections of Vernonieae in the world. DNA data will be generated using a high-throughput sequencing method, which has been proven to reconstruct evolutionary relationships among species in this group.

Detailed analyses will be conducted on a set of more than 150 macro- and micromorphological characters, including pollen. These data will be analyzed using an integrative approach to resolve generic limits and determine the accurate placement of species of Eastern Hemisphere Vernonieae in an evolutionary framework. Results will inform an expansive, first-of-its-kind toolkit for the Global Compositae Database and associated taxonomic resources to facilitate collections management, help train the next generation of taxonomists, and advance collective knowledge regarding diversity and evolution of these enigmatic plants.

All work will be carried out in collaboration with local botanists and students to develop local expertise and support a growing international network of taxonomic experts, who will advance shared goals for Compositae systematics.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.