Tall or Giant or Smooth Goldenrod, verge d’or géante
Solidago giganteaAit. is native to at least seasonally moister soils, flood plains, ditches, depressions, open woods, and thickets of eastern Canada and the U.S. and moist depressions in grasslands and parklands on the Great Plains. It is usually the least hairy species of theS.canadensiscomplex, and has a more open branched, broadly secund conical inflorescence that is less leafy thanS. lepida.辱岹().
Work done since FNA revealed thatS. giganteacan be sometimes somewhat glandular in the inflorescence making it harder to separate fromS. lepida. In a large prelimary multivariate study by the Astereae Lab,S. giganteaԻS. lepidadid not separate as well as expected using degree of glandularity to define the species. Published results were much stronger when specimens were assigned toS. giganteaon the basis of the inflorescence branching pattern, i.e. "looked likeS. gigantea" (Semple et al. 2017). Cronquist (1994) stated thatS. giganteawas clearly distinct from theS. canadenis/lepidacomplex, but sparsely glandular tetraploids (2InI=36) in New Brunswick can be similar toS. fallax.fallax, and hexaploids on the western edge of the Great Plains and into the mountains in British Columbia, Washington, Idaho and Montana can be difficult to distinguish fromS. 辱岹.salebrosa. There also appear to be some hybrids betweenS. lepidaԻS. gigantea.shinnersiiin Alberta, Saskatchewan, and Manitoba along the forest-prairie ecotone.
Several varieties have been described within the species. The hexaploid prairie plants are treated here asS. gigantea.shinnersiiBeaudry (syn: S. shinnersii (Beaudry) Beaudry).Solidago gigantea.leiophyllaFern. includes plants with smooth leaves lacking hairs on both surfaces. Neither variety was recognized by Semple and Cook (2006 FNA). The following are treated as synonyms of the typical eastern.gigantea:Aster latissimifolius (Miller) Kuntze .serotinusKuntze;Doria dumetorum(Lunell) Lunell;D. pitcheri(Nuttall) Lunell;Solidago cleliaeDC.;Solidago serotinaAit. f.huntindonensisBeaudry;S. gigantea.leiophyllaFernald;S. giganteasubsp.serotina(Kuntze) McNeill;S. gigantea.serotina(Kuntze) Cronquist;S. pitcheriNutt.;S. serotinaAit. 1789, not Retzius 1781;S. serotina.gigantea(Ait.) A. Gray;S. serotina.minorHook.;S. serotinoidesÁ. Löve & D. Löve;S. somesiiRydberg.
Multivariate work by Semple et al. (2017) onS. giganteaindicates support for recognizing the broader leaved hexaploid asS. gigantea .shinnersii: syn:S. shinnersii(Beaudry) Beaudry. This variety is found across the prairies and into the valleys of southeastern British Columbia, eastern Washington, northern Idaho and western Montana. The typical variety is eastern and diploid (2n=18) and tetraploid (2n=36).Martino et al. (2020) concluded that overlaps in ranges of morphological traits did not support recognition of .shinnersii, based on the traits considered by their study. Further work is needed.
Semple et al. (1984) summarized the pattern of ploidy distribution in the species based on a limited sample size concluding that diploids were confined to a zone running from eastern Texas to Nova Scotia but absent for the most part in the midwestern states. After several more decades of sampling, it is now clear that diploids in .giganteaoccur through much of the range of the variety but are less common than tetraploids accept in the southeastern portion of the range on the outer piedmont and coastal plain where diploids are most common or exclusive. Hexaploids (2n=54) occur on the prairies and into the mountains in the Pacific northwest; these are all .shinnersii. Morton et al. (2019) published chromosome number counts for 154 individuals ofSolidago giganteafrom Canada, England, France, and the United States. A very large sample size was used in Martino et al. (2020) who combine published chromosome count data and DNA sequence data SNP indicators of ploidy level to explore ecological features of diploid, tetraploid and hexaploid cytotypes across the species's range in North America. Martino et al. (2020) found more habitat differences separating hexaploids from the other ploidy levels, while habitat differences between tetraploids and diploids occurred but were weaker. This indicates that the evolution of hexaploidy in S. gigantea allowed the species to greatly expanded its range westward.
Solidago giganteawas not included in the treatment ofSolidagoin the Flora of China (Chen and Semple 2011). However, an image posted on Chinese web site (© Benjamin Liu) seen more recently clearly shows that the species is present in China as an invasive and is like tetraploid. Solidago giganteais invasive in Europe, Japan, South Africa and other locations.
Solidago gigantea was included in strongly supported clade S. sect. Unilaterales subsect. Serotinae (Rydb.) Semple & J.B. Beck along with S. chilensis and S. microglossa (Semple and Beck 2021; Semple et al. 2023).
Last revised 16 April 2025 by J.C. Semple
© 2025 J.C. Semple, including all photographs unless otherwise indicated
1-8.Solidago gigantea.1-5. var. gigantea. 1. Tall plants, Blue Ridge, North Carolina. 2. Open, few branched inflorescence, Semple 11523, New Brunswick. 3. Smooth, waxy stem, Nova Scotia. 4. Stem leaf, S 11523. 5. Var. shinnersii, Morton NA14215 TRT, Manitoba. 6. Heads, Blue Ridge, North Carolina. 7. Shoots along Rhine R., Cologne, Germany. 8. Range map.
Semple, J.C., H. Faheemuddin, M. Sorour, and Y.A. Chong. 2017. A Multivariate studies ofSolidagosubsect.Triplinerviaein western North America: TheSolidago lepidacomplex (Asteraceae: Astereae). Phytoneuron 2017-47: 1–43.
Morton, J.K., J. Venn and J.C. Semple. 2019 [2020]. Chromosome number determinations inSolidago gigantea(Asteraceae: Astereae). Rhodora 121 (4): 347-352.
Martino, M., J.C. Semple, and J.B. Beck. 2020. Two cytoype niche shifts are of different magnitude inSolidago gigantea. Amer. J. Bot. 107: 1567-1576.
Semple, J.C. and J.B. Beck. 2021. A revised infrageneric classification ofSolidago(Asteraceae: Astereae). Phytoneuron 2021-10. 1-6.
Semple, J.C., McMinn-Sauder, H., Stover, M., Lemmon, A., Lemmon E., and J. B. Beck. 2023. Goldenrod herbariomics: Hybrid-sequence capture reveals the phylogeny of diploidSolidago. Amer. J. Bot. 110: e16164. https://doi.org/10.1002/ajb2.16164