Solidago rupestris

Rock Goldenrod

Solidago rupestris Rafinesque is the small-headed member of subsect. Triplinerviae. The involucres are 2–3 mm high and the ray lamina only 1–2 mm long (Semple & Cook 2006 FNA).  This species is similar to S. gigantea but typically has narrower leaves.  It is similar to S. canadensis but with smaller heads and sparser pubescence.  It is uncommon, occurring on riverbanks in scattered disjunct populations with an apparent gap between eastern and western areas of the range.  There are only two chromosome counts, one diploid (2n=18, TN) and one tetraploid (2n=36, KY).  It blooms earlier than most taxa in subsect. Triplinerviae; July-August (September).  Semple and Frye (2017) reported the species' occurrence in West Virginia. Semple (2023) compared S. ruprestris to S. canadensis and S. gigantea in a multivariate analysis; S. rupestris was more similar to S. canadensis than S. gigantea, and more similar to S. canadensis var. hargeri than to S. canadensis var. canadensis.