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Common Ragweed, Hay-Fever Culprit: Weed Identification

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Picture of a young common ragweed plant.

Picture of a young common ragweed plant. Click the picture to access the mini-photo gallery for more pictures.

David Beaulieu

Taxonomy of Common Ragweed:

Plant taxonomy classifies common ragweed as Ambrosia artemisiifolia. Although its giant relative (Ambrosia trifida) is a very different-looking plant from the common variety, both are responsible for hay fever.

Plant Type:

Common ragweed is an annual broadleaf weed. So is its taller relative (mentioned above), which you can read about in my full article on giant ragweed.

Characteristics of Common Ragweed:

Common ragweed is a rather unremarkable plant. That's why the lovely goldenrod is commonly blamed for causing "hay fever," when common ragweed is the real culprit. Goldenrod and common ragweed both bloom in late summer-early fall. Being by far the more conspicuous of the two, goldenrod has become the scapegoat for hay fever, while the true villain goes unnoticed, lurking in the grass. The most you can say for common ragweed's appearance is that it bears an intricately toothed leaf (see photo). Note that, in addition to causing hay fever, this villain can also cause a skin rash (see below).

Weed Identification: What Common Ragweed Looks Like:

Click on the picture (above right) to open the mini-photo gallery, where you'll see a picture of an individual leaf from a common ragweed plant, to aid you in your weed identification. Common ragweed's tannish-green flower stalks are inconspicuous. This major source of hay fever can reach 1'-6' in height. I also offer a larger picture here showing what ragweed looks like.

Where Common Ragweed Grows:

The plant is indigenous to North America. It can be found in every state in the U.S. except for Alaska, and it is widespread in Canada, too. The plant thrives in disturbed soils and is frequently found along roadsides.

Getting Rid of Common Ragweed: Eradication:

Since it spreads via seed, efforts at getting rid of common ragweed (and thereby reducing hay fever) should focus on preventing seed production. As a bonus, if eradication occurs prior to flowering, you'll reduce hay-fever pollens -- at least in your own yard! Hand-pulling is the best method of getting rid of common ragweed for homeowners. The plants are easy to pull, as they have shallow root systems, so put your garden gloves on, killer, and do some weeding!

Name Origin for Common Ragweed:

"Ragweed" is a reference to the ragged (i.e., deeply indented) look of its leaves. The specific epithet of its scientific name, artemisiifolia, refers to its foliage, whose shape resembles another plant, artemisia.

Common Ragweed, Hay Fever and Skin Rash:

Together, common ragweed and giant ragweed account for most of the hay fever experienced in North America in the fall. Symptoms of hay fever are sneezing and runny nose, along with itchy eyes.

Although the name, "hay fever" alludes to the "haying" season (i.e., fall), people often refer to allergies experienced at any time of year as "hay fever." Thus birch trees, for example, are spoken of as a major source of hay fever in eastern North America, even though the hay fever resulting from their pollen occurs in spring, not fall.

Your efforts to eradicate common ragweed will presumably be limited to your own yard. So no matter how good a job you do at eradication, the pollen from common ragweed will still be in the air. What is a hay-fever sufferer to do? Stay inside all September? Well, at least you can try to minimize your outdoor activities when the pollen count is highest (generally between 10 a.m. – 4 p.m.). This practice won't eliminate your hay fever, but it may make hay fever a bit easier to endure.

While more often associated with hay fever, common ragweed is also one of the plants that cause rashes. I learned about this association with skin rashes (allergic contact dermatitis) from About's Dermatology Guide, Heather Brannon, M.D. Between the hay fever and the rashes, this plant is thoroughly qualified for its place in my "Hall of Infamy" of noxious weeds.

See my larger, closeup pictures of ragweed for further help with identification.

Back to > Index to Common Lawn Weeds

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