Tall Goldenrod vs Canada Goldenrod
This guide is under construction and has not been published yet. It may have errors. When in doubt, double-check other sources for definitive ID.These two species are visually similar, and can be devilishly hard to tell apart where their ranges overlap. They can usually be definitively told apart by degree of serration on upper leaves, and by involucre length, and there are average differences in pubescence. Some plants can be identified as S. altissima by the presence of ball galls on the stem. S. altissima ranges much farther south and west, and tolerates drier conditions. S. canadensis ranges farther north, and prefers moister conditions.
Tall Goldenrod (Solidago altissima) | Canada Goldenrod (Solidago canadensis) |
A common, aggressive perennial of rich, sunny, disturbed sites, native to a wide range across North America. | One of the most common and widespread goldenrods of northeastern North America. |
 Stems may have large, conspicuous galls on them. If you see such a gall, you can know it is this species. Photo © Andrew Sebastian, CC BY 4.0. |  Stems never have ball galls. Photo © David McCorquodale, CC BY 4.0. |
 Leaves average less conspicuously toothed, with minute, barely-visible teeth, and teeth often confined to the half of the leaf closest to the tip and absent or greatly reduced in the base half. Often, upper leaves may lack teeth entirely, especially right under the inflorescence. Photo © Cole Shoemaker, CC BY 4.0. |  Leaves average more conspicuously toothed; leaves remain toothed even higher up on the plant, to right under the inflorescence. Leaves in the inflorescence may lack teeth. Photo © Eric Lamb, CC BY 4.0. |
 Involucres (clusters of bracts under each flowerhead) are longer (2.5–4.5mm) and tend to look narrower. Photo © Derek, CC BY 4.0. |  Involucres are shorter (1.7-2.5mm, rarely to 3mm) and tend to look more stout. Photo © Ryan Sorrells, CC BY 4.0. |
 Lower portion of the stem averages more hairy. Stem is usually hairy the whole way to the base, occasionally nearly smooth. Photo © Michael J. Papay, CC BY 4.0. |  Lower portion of the stem averages less hairy, and is more likely to be nearly smooth. Photo © Ryan Sorrells, CC BY 4.0. |
 Leaf underside has more hair along veins, but still has some hair throughout. As a result, leaf undersides often look slightly paler. Photo © Derek, CC BY 4.0. |  Leaf underside usually only has hair along the veins. As a result, leaf undersides often look slightly deeper green. Photo © jyoung2399, CC BY 4.0. |
 Usually blooms later (Mid-to-Late Aug-Nov, peaking Sep-Early Oct) Often is among the last plants blooming. (Photo from December in NC.) Photo © Ken Kneidel, Public Domain. |  Usually blooms earlier (Late July-Early Oct, peaking Aug-Sep). (Photo from August, PEI, Canada) Photo © scaup, CC BY 4.0. |
Additional Notes
Some sources cite the inflorescence shape but this trait is so variable on both species that it is not always reliable for ID.WARNING: Different authorities use wildly different classification schemes for the Solidago genus. Many older authorities lump S. altissima in with S. canadensis as a subspecies or variety. These authorities usually consider the taxa we consider to be sub-taxa of S. altissima to be sub-taxa of S. canadensis instead. Even among authorities that recognize these two species as separate, however, there are different treatments used.
References & External Resources
These short lists show only links helpful for ID. For a complete list of references and resources also covering other aspects of ecology, visit the links section of the full article on each plant, which is the first entry here.
