Years ago I found a small goldenrod high in the Ricky Mountains. It was a very nicely shaped little thing, only about ten inches tall. I thought it would be great in a rock garden, and brought it back to Michigan. At our lower altitude, that pretty little thing got a lot taller than I am. it was Canada goldenrod, and is certainly beautiful, but it isn't the best garden choice. It spreads freely, and has produced a couple of hybrids in my garden. This is Canada, I suspect, because of its species name. Back when it was named in 1753, borders were different, and many plants from North America became canadensis, even though the specimens often came from below the modern border. Some of those don't even occur in modern Canada. This species was much used by Indians, including as a smoke plant.