How can I tell if a plant is goldenrod or ragweed?

Question

My husband suffers from bad hay fever in the fall. We've always thought goldenrod is a major contributor. Recently we were told that ragweed, which looks similar, is more likely to cause the allergy and its related discomfort.

In our yard there are many plants with clusters of bright yellow flowers, which bloom in the late summer, early fall. They're lovely, and the birds, bees and butterflies like them. Assuming that they're goldenrod, and making my husband sick, I usually pull them shortly after they bloom. If indeed they are goldenrod, but not likely to be the allergen, I'd prefer to leave them until they've completely gone by. However, if they're ragweed, I'll know that I should pull them before the pollen flies.

I don't like removing any flowers, so understanding how to tell what they are would help me make an informed choice as to how to proceed next fall.

I'd appreciate a good definition of both goldenrod and ragweed, with some identifying characteristics, and links to pictures.

I'd also like to know if my own are goldenrod, ragweed, or both. Unfortunately, my pictures are very blurry, especially the flowers, so an identification may not be possible. I have a few other pictures with different views, but the quality isn't much better. They went by a number of weeks ago, so I can't get you anything new. Clicking on them will make them bigger and more close-up, in case that helps.

Answer 1

None of these pictures show ragweed. These are all goldenrod. Goldenrod can be allergenic but has pollen too heavy to be carried by wind and is very much unlikely a culprit of hay fever.

Ragweed has dissected, feathery leaves and less showy flowers than these. Alas, even if you pulled all the ragweed in your yard (if you had it) it would not help allergies. If it grows in your neighbourhood's proximity, it will affect those allergic to it.

Answer 2

I did an answer already, then realised you're asking about ragweed, not ragwort.

Ambrosia trifida (ragweed) has variable leaves, sometimes palmate, sometimes tripartite, often with a few oval leaves as well, and the flowers are yellow, usually upright spikes. It produces spiny burrs which stick to clothing and footwear, which is one of the ways it spreads. Images and info here: Giant Ragweed (Ambrosia trifida).

As far as I can tell from your photos, none appears to be ragweed, they mostly all look like various forms of Solidago (goldenrod) but perhaps you could compare the image of Ambrosia with your own plants; if one of them does produce spiny burrs, then that needs examining closely, but I'm not seeing any leaves which fit the picture for ragweed. I'm not sure what the plant in the bottom right photo is - its not Solidago, but it doesn't look like ragweed either.