A phylogenetic hypothesis of American Vernonieae based on three molecular regions (ITS, ndhF, rpl32-trnL) and on a morphological dataset reveals the existence of four main lineages. Three of these lineages correspond, with a few adjustments, to subtribes Chrestinae, Lychnophorinae, and Vernoniinae. The fourth lineage, which has never been recognized at a taxonomic rank due to the lack of morphological characterization, is mainly composed of taxa usually included in Lepidaploinae and Elephantopinae as well as a number of genera traditionally placed in other subtribes (Chrestinae, Piptocarphinae, and Vernoniinae). The relationships between these lineages are still not satisfactorily resolved. In order to keep the Lychnophorinae monophyletic, two small subtribes (Centratherinae, Sipolisiinae) and three monotypic genera (Albertinia, Blanchetia, and Gorceixia) have to be transferred to Lychnophorinae, which has the presence of heliangolide in aerial parts as a synapomorphy. Even though syncephaly has been historically used to delimit the subtribe Lychnophorinae, our results show that this character probably appeared independently three or four times in the evolution of American Vernonieae. The formation of the syncephalium, in each case, seems to be related to different biological functions: attractive (Chrestinae), disseminative (Rolandrinae), or protective and, to a lesser extent, attractive (Lychnophorinae).
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Vol. 40 • No. 1