This short piece was published on our former blog in 2015.
"In Finland, you have to pay good money for goldenrod," says Dr. Jim Quinn, biology professor at McMaster University. People need to understand tht golden rod is not the cause of your allergies. Ragweed is likely the culprit.
"So why the confusion?" I ask Quinn.
Quinn explains that there is a natural "spurious correlation" between goldenrod and ragweed. The idea of spurious correlation is taken to mean roughly that when two variables correlate, it is not because one is a direct cause of the other but rather, because they are brought about by a third variable: pollen causes hay fever.
Both blooming in late summer, "ragweed is cryptic. You don't notice it, but when golden rod blossoms it's obvious with it's masses of yellow flowers," says Quinn. And it gets the blame.
But as this professor reminds his first year class, "Think form and function." Goldenrod pollen is pollinated by insects so that is why it is sticky and heavy. Ragweed pollen is airborne.
The ragweed plants is similar looking to the common plantain weed. Watch for dark green plants with deeply cut leaves.
Ragweed is an exotic, grows well along roadsides and cleared land in urban settings: "It's connected to human habitation," Quinn says. "Golden rod is not much of an opportunist, and favours open habitat, farm land."
Do you want to discourage ragweed? A thriving community of native plants will do the trick: "As soon as they get competition, they tend to go away," Quinn advices.
Read more about the differences in plants here