Euthamia (Nutt.) Cassini in F. Cuvier is a small genus of erect, herbaceous perennials native to North America. Sierren (1981) revised the genus and recognized nine eastern species and one western species. Haines (2006 Flora North America) recognized only five species. Euthamia was incorrectly included in Solidago by many authors for a more than a century. Cronquist (1981) accepted the distinct generic status for this group of species on the basis of morphology and leaf anatomy (Anderson and Creech 1975).
Lane et al. (1996) showed that the on the bases of cpDNA, Euthamia was phylogenetically not close to the true goldenrods with a number of other genera more closely related. Zhang (1996, Ph.D.; summarized in Semple, et al. 1999) obtained the same results in his cpDNA RFLP study of the goldenrods. In the ITS sequence analyses in Beck et al. (2004) and Brouillet et al. (2009), Euthamia grouped with Gundlachia, Xylothamia, Gutierrezia, Gymnosperma, Amphiachyris, Bigelowia and Thurovia in the Solidagininae II Clade, not with Solidago in the Solidagininae sensu stricto.
Unfortunately, the practice of placing the grass-leaved goldenrods in Solidago continues and leads to errors in interpreting the results of ecological studies.
Species of grass-leaved goldenrods have erect stems bearing linear grass-like leaves with 1-7 well-developed veins and heads borne in clusters.
revised 1 November 2013 by J.C. Semple
© 2013 J.C. Semple, including all photographs unless otherwise indicated