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

OVERVIEW:

The biodiversity crisis is among the most urgent global threats facing humanity. Confronted by this challenge, it is critical to understand plant diversity and assess conservation priorities. Exacerbated by the taxonomic impediment, species are going extinct before they are discovered and described.

Increased access to digitized collections and their data may offer a solution to the taxonomic impediment and the Global Compositae Database (GCD) was established for this purpose. Nearly one in every ten species of flowering plant belongs to the sunflower family (Compositae). Classification of Compositae is complicated by the number of species (more than 33,000) and genera (ca. 1,800).

One of the largest tribes in this family, Vernonieae, has proven so intractable for taxonomic revision it is often referred to as the "evil tribe." Historically, more than 1,000 of the ca. 1,500 species in Vernonieae were recognized in the genus Vernonia. This genus has recently been recircumscribed to include just 21 species in the Americas, which instigated the necessary reclassification of ca. 1,000 species from Vernonia to other genera.

Much of this work has been completed in the Western Hemisphere, but few studies have been undertaken for the more than 700 species of Eastern Hemisphere Vernonieae. At least 200 Eastern Hemisphere species currently remain in Vernonia but because of poor generic delimitation in this tribe it is unclear in which genus they belong. This proposal will address the taxonomic impediment in Eastern Hemisphere Vernonieae using novel and transformative approaches to taxonomy that comprise five objectives: (1) overcome critical sampling gaps preventing integrative taxonomy of Eastern Hemisphere Vernonieae through detailed herbarium study and five collecting expeditions; (2) develop a robust evolutionary framework of Eastern Hemisphere Vernonieae with phylogenomics and explore a suite of macro- and micromorphological characters to facilitate taxonomic revision; (3) undertake systematic study that combines phylogenomic and morphological data to resolve generic placement of all species of Eastern Hemisphere Vernonieae; (4) disseminate taxonomic information via the Global Compositae Database; and (5) provide training for the next generation of plant systematists and taxonomic experts in Compositae.