If you don't have a hard, cold place in your heart for ragweed, I can only conclude that you either a) are one of the lucky 70+ percent of the population that doesn't get hay fever, or b) don't know what's causing you to sniffle constantly from August into September. I do have hay fever, and I know one of the worst perpetrators. Permit me to tell you about it.
It's the non-descript green flowers that are my nemesis: instead of developing pretty, frilly things to attract pollinators, ragweed developed the ability to produce massive amounts of airborne pollen that floats around looking for other ragweed plants to fertilize. If you look closely at the individual flowers in a stalk, they're all pointing down, so they can just drop their pollen on the breeze. A billion grains of pollen per plant, in fact.
It's the carpet bombing strategy of the plant world.
These innocent grains of pollen are dependent on the wind to take them where it may. And wind goes many places. Down your street, say. And, eventually, up your nose. And then, as WebMD describes it,
Your immune system reacts to them as if they were a threat...Specialized immune cells start churning out antibodies to proteins in the pollen. The ensuing cascade of biochemical reactions floods the bloodstream with histamine, a compound that causes all-too-familiar allergy symptoms...[including] sneezing, sniffling, nasal congestion...red, puffy eyes, itchy throat, and even hives.
Pass the antihistamines, please.
Ironically enough -- did you notice this above? -- the scientific name of the ragweed genus is Ambrosia. A contributor to the Wikipedia entry on ragweed speculates that this might be for the "immortal" root of the word ambrosia. But these plants are annuals -- they live less than a year. That's why they have work so hard at reproducing. Any other guesses on what Linnaeus was thinking with that name? There's a good chance he had no idea about the link to hay fever.
In your yard: This is a native plant that serves as food for many insects and birds. But it's doing fine on its own in the wild, thank you very much. You really, really don't need to grow more. Please.
*Thought ragweed had yellow flowers? You're not alone, judging from my search for photos for this post. But that's goldenrod. More on that next week!