Subtribal classification and generic delimitation among Eastern Hemisphere ironweeds (Vernonieae, Compositae)

An integrative taxonomic approach to tackle the 'evil tribe'.

Vernonia djalonensis flowers are small with many thing, individually separated petals that spike away from the centre.

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.

Classification in Vernonieae has often relied upon microcharacters (e.g., pollen and trichomes). Pollen characters in particular serve as the basis for many generic diagnoses. Tribe Vernonieae displays a large diversity in pollen structure, and palynological features remain the most reliable and consistent characters to delimit subtribes and genera throughout the history of its classification. Since the original description of six pollen types more characters have been incorporated and now about 10 main pollen types are recognized.

This project will use an integrative approach that combines an extensive documentation of macro- and micromorphological characters within a phylogenomic framework in novel and transformative ways. As a result, we will produce a revised subtribal classification for Eastern Hemisphere Vernonieae and clarify generic boundaries. Emphasis will be placed on continental Africa, Madagascar, and Asia, where most of the diversity of Eastern Hemisphere Vernonieae is centred. The work will simultaneously lead to a comprehensive, unified, and publicly accessible online database that will incorporate taxonomic resources in novel ways that can be expected to set a standard for other taxonomic groups, facilitate scientific collaboration, and help train the next generation of plant taxonomists.


  • Overcome critical sampling gaps preventing integrative taxonomy of Eastern Hemisphere Vernonieae through detailed herbarium study and five collecting expeditions.
  • Develop a robust evolutionary framework of Eastern Hemisphere Vernonieae with phylogenomics and explore a suite of macro- and micromorphological characters to facilitate taxonomic revision.
  • Undertake systematic study that combines phylogenomic and morphological data to resolve generic placement of all species of Eastern Hemisphere Vernonieae.
  • Disseminate taxonomic information via the Global Compositae Database.
  • Provide training for the next generation of plant systematists and taxonomic experts in Compositae.
  • Publication of evolution of microcharacters in Eastern Hemiphere Vernonieae
  • Publication of taxonomic and nomenclatural novelties
  • A new subtribal classification of Eastern Hemisphere Vernonieae
  • A model for the curation and dissemination of integrative, digital taxonomic data in Vernonieae, Compositae (Global Compositae Checklist database)


  • Morgan Gostel (PI), Botanical Research Institute of Texas, USA
  • Marie-Cakupewa Fundiko, Jardin Ethnobotanique Kivo, D.R. Congo
  • Nicola Bergh, South African National Biodiversity Institute, South Africa
  • Pimwadee Pornpongrungrueng, Khon Kaen Univeristy, Thailand

NSFDEB-NERC: Subtribal classification and generic delimitation among Eastern Hemisphere ironweeds (Vernonieae, Compositae) project (NE/X00984X/1)