VernoniasubgenusAustrovernonia, a new subgenus from South America (Compositae, Vernonieae, Vernoniinae).

Abstract

Vernoniaincana Less. and V.echioides Less. are two semi-aquatic species from southern South American that are referred to as “the semi-aquatic Vernonia of South America” and they have been, until now, retained as members of Vernonia mostly because each had some unusual characters that made them hard to place. Based on an ongoing molecular study, we can now say that V.incana is the sister taxon to all true Vernonia and can therefore be responsibly left in Vernonia but, because of its morphological and geographic differences, it is now assigned to its own subgenus: Vernonia subg. Austrovernonia. Vernoniaechioides is not closely related to V.incana and is now part of a separate investigation. This placement of V.incana as sister to the true Vernonia species brings up the possibility of a South American root for the Vernonia clade and perhaps indicates a propensity in the lineage for growing in or near water. The species V.incana is lectotypified.