Northern or Rocky Mountain goldenrod , verge d’or à rayons nombreux

Aster multiradiatus (Aiton) Kuntze; Solidago algida Piper; S. cusickii Piper; S. dilatata A. Nelson; S. multiradiata var. arctica (de Candolle) Fernald; S. multiradiata var. scopulorum A. Gray; S. rubra Rydberg; S. scopulorum (A. Gray) A. Nelson; S. virgaurea Linnaeus var. arctica de Candolle; S. virgaurea Linnaeus var. multiradiata (Aiton) Torrey & A. Gray

Plants (3–)10–30(–80) cm; caudices branched. Stems 1–10(–30+), decumbent to erect, slender, tufted, proximally glabrous or sparsely hairy, densely short-hispido-strigose in arrays. Leaves: basal and proximal cauline petiolate; petioles winged, margins ciliate; blades linear-oblanceolate to spatulate, 10–170 × 3–30 mm, serrate to crenate near apices; distal cauline sessile; blades sometimes subclasping stems, ovate to linear-lanceolate, 16–20 × 7–11 mm, margins often distinctly ciliate. Heads 4–75(–100+) , not secund, in dense, round-topped corymbiform arrays; branches white villous. Peduncles 5–6 mm, villous; bracteoles 0–2, linear-lanceolate to lanceolate. Involucres 4–8 mm. Phyllaries unequal to subequal, outer linear-lanceolate to lanceolate, lengths ± ² / 3 inner, margins ciliate, apices acute to attenuate. Ray florets 12–18; laminae 3–4 × 0.5–1 mm. Disc florets 10–35; corollas 3–5 mm, lobes 0.3–1 mm. Cypselae 1.5–4 mm, sparsely to moderately strigose; pappi 3–4 mm (inner bristles clavate). 2n = 18, 36.

Flowering Jul–Sep. Tundra and tundralike habitats, alpine slopes and meadows; 0–3700 m; Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Nunavut, Ont., Que., Sask., Yukon; Alaska, Ariz., Calif., Colo., Idaho, Mont., N.Mex., Oreg., Utah, Wash., Wyo.

Solidago multiradiata is the North American species most closely related to S. virgaurea, the type species of the genus, native to mostly arctic and alpine regions of Eurasia. Plants of S. multiradiata from the Rocky Mountains have been treated as var. scopulorum; they differ so little from those of other parts of the range that recognition of the variety without further support does not appear justified.

Solidago heterophylla Nuttall ex A. Gray is an invalid name (pro synonym of S. multiradiata var. scopulorum) that pertains here.