Rock goldenrod

Aster rupestris (Rafinesque) Kuntze; Solidago canadensis Linnaeus var. rupestris (Rafinesque) Porter

Plants 50–150 cm (solitary or clustered); rhizomes creeping, elongate. Stems 1–10+, erect, proximally glabrous, increasingly puberulent distally into arrays. Leaves: basal 0; mid and distal cauline numerous (sometime 100+ per stem) , crowded, sessile or subsessile; blades linear-elliptic, mostly 50–120 × 6–12 mm, tapering at both ends, margins remotely serrulate or subentire, 3-nerved, faces glabrous or sometimes puberulent abaxially on midnerves. Heads 80–900+, in paniculiform arrays, branches recurved, secund. Peduncles 1–3 mm, sparsely strigose; bracteoles linear, 1–3. Involucres narrowly campanulate, 2–3 mm. Phyllaries in 3–4 series, linear-lanceolate, strongly unequal, midribs raised, enlarged apically, apices acute to usually obtuse or rounded, apically ciliate. Ray florets mostly 7–11, 1–2 × 0.1–0.2 mm. Disc florets 2–7; corollas 2–3 mm, lobes 0.4–0.6 mm. Cypselae (narrowly obconic) 1–1.5 mm, sparsely strigillose; pappi 2–2.5 mm. 2n = 18, 36.

Flowering Jul–Sep. Riverbanks; 0–200+ m; Ind., Ky., Md., Pa., Tenn., Va.

Solidago rupestris is similar to S. canadensis in head size but with fewer rays, and it is vegetatively more like S. gigantea. It is uncommon, occurring in a series of disjunct populations with an apparent gap between eastern and western areas of the range.