A genus of 2 species, perennial herbs, of eastern North America. Hasteola (Synosma) has been treated as a small genus of perennial herbs (consisting of Hasteola suaveolens and the FL peninsular endemic, H. robertiorum L.C. Anderson), but Pelser et al. (2007) included it in Senecio based on an interpretation of phylogenetic results. Simultaneously, Kadereit & Jeffrey (2007) retained it as a genus. Pruski (2021) defended it as a genus.