Northern or Rocky Mountain Goldenrod
Solidago multiradiata Ait. is native to tundra and tundra-like habitats, alpine slopes and meadows across northern North America from Alaska to Newfoundland and northern Nova Scotia and south in the Rocky Mountains to Arizona and New Mexico and in the Sierra Nevada Mts. in California. It also occurs in eastern Siberia. The species is distinguished by heads usually arranged in ± flat-topped or rounded inflorescences and its usually subequal, acute to acuminate phyllaries (Semple & Cook 2006 FNA). The species includes diploids and tetraploids (2n=18, 36). Semple and Chmielewski (2022) reviewed all counts and published a cytogeography map for S. multiradiata, S. leiocarpa and S. spithamaea. Diploids of S. multiradiata occur throughout the range and are the only ploidy level known in southern portion of the range in the western mountains; tetraploid are common or dominant in the more northern portion of the range in the west.
Solidago multiradiata is the North American species presumed to be most closely related to S. virgaurea, the type species of the genus, native to mostly arctic and alpine regions of Eurasia. In eastern North America, tetraploid S. leiocarpa and hexaploid S. spithamaea are closely related to S. multiradiata.
Plants of S. multiradiata from the Rocky Mts. have been treated as var. scopulorum A. Gray; they differ little from plants of other parts of the range and recognition of the variety without further support does not appear justified (Semple & Cook 2006 FNA).