White goldenrod, Silverrod
Solidago bicolor L. is widely distributed in eastern North America (Semple & Cook 2006). The species is disguished by having white-rayed heads arranged in a wand shaped inflorescence. It is very similar to S. hispida, which has been included in the species by some authors. The two species can occur together, but I have not seen hybrids between them. The species is only known at the diploid level 2n=18. Semple and Cook (2022) published cytogeography maps for S. bicolor and related species.
Semple (2016) documented a Solidago bicolor × S. brendiae hybrid using multivariate morphometric analysis of specimens of S. bicolor, S. brendiae and S. canadensis. The hybrid was first reported by Hinds (1984) as S. bicolor × S. canadensis; the subsect. Triplinerviae parent was actually S. brendiae.
Semple et al. (2017) presented a multivariate study of the S. bicolor complex that includes S. hispida, S. porteri, S. roanensis, and S. sciaphila and more broadly S. erecta. Semple and Beck (2021) placed S. bicolor in S. ser. Albigula of S. subsect. Erectae.