Help me ID ragweed in the field, from a distance

February 10, 2015 10:56 AM

I am allergic to ragweed. I have no clue what it looks like. Give me your best pics, tips, and secrets, oh people of metafilter with Plant Foo.

You don't need to read the long background. Just tell me how to ID it. But here is how I am 49, know I am allergic, and can't ID it:

I lived in Kansas in my twenties, but the reasons I was miserable there were not identified while I lived there. It is ragweed central. I was always sick there. I was on steroids every spring to keep me out of the ER and left for 4-8 weeks to "visit family" (aka BREATHE) every year. Fourteen years ago, when I was at death's door, they ran a jillion tests, including your standard allergy panel. The only thing the doctors officially believe me to be allergic to is ragweed (and never mind the jillion other things that make me itch and respond well to antihistamines).

The past few days, my sons and I all feel miserable in the same way we felt when we lived in Kansas. Yesterday morning, I had hives on my right hand. Not much causes me hives. I am non-reactive to poison oak, poison ivy and sumac (stuff that puts my brother in the ER). So I strongly suspect I had physical contact with ragweed yesterday morning. I spent the day wishing I were dead. 2015 is turning into a year I would like to put back in the box, take back to the store, and get a full refund on. Please help me ID this plant so I can not stupidly touch it again.

(I have googled pics on the Internet and that helps, but I want more tricks up my sleeve, cuz, gawd. Yesterday was So. Freaking. Miserable.)

Thanks!

posted by Michele in California to Science & Nature (9 answers total)

Best answer: There are 17 types of ragweed in the continental United States, and the pollen is extremely lightweight and can remain airborne for days and travel 400 miles. It is virtually impossible to avoid when in season. You can get contact dermatitis just from the pollen grains; you don't need to touch the plants. The pollen is the allergen.

However, ragweed flowers from August to October in California, so it's extremely unlikely that you were in contact with the pollen this past week.

Many weather stations also report the prevalence of particular allergens; one near to you may help you identify more likely culprits. Google "[my location] pollen count" or "[my location] allergy forecast."
posted by Eyebrows McGee at 11:25 AM on February 10, 2015 [2 favorites]

Best answer: Ragweed grows about 2-3 feet tall, and those spiky parts on the top you see in the pictures? Bright yellow. Can be found in ditches, fields, along roadways; usually multiple plants --- not singles, you'll see groups or even entire fields of the stuff. So: if you see a patch of tallish weeds with pretty yellow strands, avoid!

For what it's worth, also avoid Queen Anne's Lace: about the same 2-3 feet tall, but with pretty white lacy discs on top.... not as bad as the ragweed (few things are!) but bad enough.
posted by easily confused at 11:26 AM on February 10, 2015

Oh, and the poison oak/poison ivy/sumac thing: I know what you mean, I've been lucky enough to be non-reactive to that stuff too. Unfortunately, it is a known thing that sometimes people suddenly, without warning, develop a reaction, after a lifetime of non-reaction. (What a bummer!) Have you been around any of those lately?
posted by easily confused at 11:45 AM on February 10, 2015 [1 favorite]

Best answer: Many people also blame goldenrod for allergy, as they often grow in close proximity, but this article articulates their differences quite nicely (includes pictures).
posted by Riverine at 12:15 PM on February 10, 2015 [1 favorite]

You don't have to have contact, as said above. It's not like poison oak/ivy. Can you take histamines regularly? That's what I do during peak allergy seasons (I have seasonal and dust allergies). Once the reaction has started it has to run its course a bit before the medicine takes hold, so I just keep it at bay by always taking antihistamine when i know things will be bad.
posted by zutalors! at 12:52 PM on February 10, 2015

Response by poster: Have you been around any of those lately?

I am around a lot of plants on a regular basis. I have almost zero Plant Foo. I cannot tell you what all I have been exposed to. Thus, this question.

Can you take histamines regularly?

I am not looking for suggestions on how to treat it. I have that angle under control. Thanks! :-)

I am just trying to figure out a) how to ID ragweed and, based on the first comment above, b) whether or not it was even ragweed I contacted. Regardless of what I contacted yesterday, I would like to know ragweed when I see it.

Also, I found this map yesterday. I currently have plans to relocate from San Diego County to a California city further north. California is generally not too bad, but San Diego County seems to be worse than most of the state. So I am glad I already, for unrelated reasons, plan to leave here as soon as 2015 quits hatin' on me and I can manage to make arrangements.

(Cali 4 Life. Unless I marry a foreigner and ditch this godforsaken, ragweed-carpeted continent.)
posted by Michele in California at 1:04 PM on February 10, 2015

Best answer: Ragweed doesn't have very noticeable flowers. They're greenish and wouldn't even register as flowers to many people. And you don't usually see a whole field of ragweed, just scattered plants or small groups of plants. Because goldenrod is so much more noticeable and blooms about the same time of year, many people think they're allergic to goldenrod when they're really allergic to ragweed. And some people may think goldenrod is ragweed. When I did a Google image search for ragweed, I noticed that quite a few of the images that came up were actually of goldenrod. One of the answers here also sounds more like a description of goldenrod to me. If you want to learn to identify ragweed, make sure you're looking at pictures of the right plant, not just whatever comes up on a Google image search. Here is a good picture and here is another one.

That said, if you have allergies in spring, I'm pretty sure ragweed isn't your only allergy. It doesn't sound like it blooms in spring even in California, and it wouldn't have been blooming in spring in Kansas. It was probably something else that gave you hives yesterday.
posted by Redstart at 1:15 PM on February 10, 2015

Best answer: Here's my photo of the commonest ragweed where I live, in Montreal. The flower is almost invisible. The plant is attractive as weeds go, and the leaves have a pleasant scent.
posted by zadcat at 1:39 PM on February 10, 2015 [1 favorite]

Response by poster: Okay, awesome! Thank you everyone, especially folks who posted links to pics. ( had previously googled something and sent that to my son and, based on what was said here, I apparently sent the wrong thing to my son. So I am really glad I asked and I really appreciate the tips about some pics on the Internet being wrong and THESE are correct.

Yesterday, I sent the link to this Ask to my son. He says he has seen that plant. I told him to find it and show me sometime (I have TERRIBLE eyesight). Also, he checked some pollen forecast site, and, yes, this area is experiencing low levels of ragweed pollen currently. We have had a long drought and we seemed to get decent-ish rain in December and January (not enough to refill all the reservoirs, but enough to make some plants happy). On top of that, it has been unseasonably warm in recent weeks. Everything is (or looks) lush, green and in bloom -- apparently even some of the ragweed.

I am going to go ahead and mark this resolved, but if you come in late and want to say something more or post more pics, please don't let that stop you.

Thanks!
posted by Michele in California at 9:39 AM on February 11, 2015