Ambrosia 2
The Common Ragweed
The sneezin' season is upon us in the region of weedom, where those who suffer ragweed allergies are spending big money on relief of their rhinitis or asthma, congestion, drippage, and itchy eyes. In 'celebration’ 🙃 let's return to the fountains of airborne pollen for a wholistic look at their benefits and detriments, concentrating on the shorter, common ragweed, Ambrosia artemisiifolia, which, coincidentally our oldest kid is presently mowing down in one of the pasture areas of the farm. He texted this pic of the flowering tops, complaining that this tough, fibrous weed is difficult to cut down in such massive quantities.
Such a consequential social irritant as ragweed is worth highlighting in its season of glory, and we can take an opportunity to look on its bright side.
You can go back to 2023 in the open archives of weedom to see a prior article about this bitter flavored ragweed as well as the larger Ambrosia trifida with its milder, 3 lobed leaves. For the non-clickers, I'll touch on the botany by repeating myself a little bit.
A main thing to remember is that Ambrosia trifida is called giant ragweed for a reason. It gets really extremely tall, 8 or more feet (2.5 - 3 meters) treelike, with ribbed fibrous stems that can really take the wind. Ambrosia artemisiifolia is 3 plus feet tall (1 meter) with often purply pigmented and very hairy stems. The hair lets you know right away that it isn't poison hemlock. The purple lets you know it's not Spanish needles (Bidens bipinnata)
Our 2 ragweeds (among about a dozen U.S. species) have very different leaves, which give them their species names. Three lobes on the giant ragweed, Ambrosia trifida leaves. The common ragweed, Ambrosia artemisiifolia are divided similarly to the plants of the Artemisia genus. Pay attention to the hairy stems so you’ll know the ragweeds from the bottom 2 weeds. Poison hemlock has finely divided leaves which are hairless and somewhat shiny, with zero hairs on the stems. and Spanish needles likewise has bipinnately divided leaves, which are also hairless and shinier than ragweed. It takes some practice to distinguish these plants when they’re young. The smell of each will help you a great deal. Poison hemlock stinks when you crush it. Ragweeds, especially common ragweed, smell a bit sharp but not unpleasant. Keep watching these weeds through their growth cycles. Finding them as they bloom is easiest, then come back to their location in the following year to see their early stages of growth, so you’ll know them anywhere. Rub the leaves so you learn their distinctive smells, and you can decide whether to remove them or use them.
Ragweed might not be more of a potent allergen than any other of the huge Asteraceae family of plants. But it has light, windborne pollen from zillions of downward facing male flowers borne on the topmost tips of the plant that is blown everywhere, including towards the female flowers down lower in the axilla (armpits) of the stems, and facing upward. This plant is well adapted for getting pollen up your nose. Our common ragweed has tiny creamy colored male flowers facing down, with the sepals above, so that the flowers appear inconspicuously green. (Giant ragweed is similar, but with yellowish blooms).
Ragweed is a monoecious, with male flowers and female flowers on the same plant, which are arranged like maize, Zea mays, which has male flowers as tassles above, and female flowers that become the ears of corn growing between the stem and leaf axilla.
Both A. trifida and A. artemisiifolia produce substances which can impede the germination of their own seeds, and inhibit the growth of new shoots. This prevents excessively dense germination and mass die-off. The main compounds to which this autotoxicity has been attributed are chlorogenic acid, vanillin, caffeic acid, and p-coumaric acid. It's possible for each Ambrosia plant to produce from 2000 to 60,000 seeds, which can survive in the ground up to 80 years. The autotoxicity, (which decreases with water rinsing, and lower seed density), serves to preserve the seed bank for gradual germination and extended survival of the species in any give area.
Ophraella communa, the ragweed leaf beetle is native to North and Central America, but migrated to Europe around 2013. Its arrival was celebrated by sneezing people who had suffered the travails of hay fever from the earlier (accidental?) migration of the ragweeds from the Americas.
A group of investigators communicated to the journal, Nature in 2020, an estimate that over a billion dollars yearly in health care costs would be saved (out of 7 billion estimated cost) in Europe due to the new presence of these ragweed eating beetles, which were reported to have destroyed 82% of A. artemisiifolia in the fields of Italy. A corresponding seasonal reduction in pollen counts was observed at the expected times of ragweed blooming. Maybe the authors of this report will be celebrating with annual beetle festivals at Summer's end.
People have expended a lot of hate on ragweed for its pollen producing talents, but there is a bright side to this plant.
Like all the other weeds, it is packed with amazing biochemistry, and it even has some food value too.
It seems that ragweed was cultivated up to about 600 years ago, when it was replaced by corn. Seeds of Giant ragweed, A. trifida have been found in archeological digs of U.S. first immigrants from 900 or more years ago. These seeds of the cultivated plant were much larger than those of todays usual weeds according to some stories which are fading from the web. One of these is the Tree of Life (tolweb.org) which even gives this Lakota name for the plant: caŋĥlóĝaŋ paŋśpaŋjela, and some traditional uses. This name describes a bulky seeded soft weed, per the speaker. One could argue whether seed collection was for food or medicinal use, given the difficult work of collecting them from the female flower pods, and we are left guessing. Seeds of A. trifida are edible and quite nutritious, with respect to protein and fat content, for those willing to do the work.
The leaves of our two ragweeds are edible, if harvested when they’re soft and young. Even most people who are allergic to the pollen could eat the leaves, but would be not be inclined towards those gathered during the blooming season! Also, this is a medicinal plant, with plenty of active chemistry that inhibits some animals from eating it, yet encourages others to eat it. The main take home is that it is not to be eaten in large quantities, and the taste of it will guide you. Boiling removes some of the bitter components, and increases the edibility. Young leaves can be simmered for about 5 min, then stirred in with some sauteed onions or garlic, and some ginger if you like. This prep suggestion comes from Vermont Pure Herbs. Expect a piney bit of flavor especially from the common ragweed. The stems are fibrous, so leave them out. If you wish to cook up the giant ragweed, you won’t need the ginger because those milder trilobed leaves possess that flavor element inherently. The anti-inflammatory compounds within these leaves do what all the best greens do: lessen the severity of pain and allergies. Most traditional sources don’t seem to mention eating the leaves of Ambrosia as food, which is odd, because the genus name itself means “food of the gods”. Consuming leaves seems to be increasing in recent years, perhaps due to people taking a cue from the livestock and conducting their own taste tests as I have done. Marie Viljoen at Gardenista is creating delicacies with the leaves of both species, and even using male flowers! of A. trifida in seasonal recipes. Those going beyond the garnish and spice levels in culinary practice, or using internally as medicine should avoid this while trying to get pregnant or during pregnancy.
There exists one European study involving a small group of rats, which showed no overt toxic effects from feeding the leaves of A. artemisiifolia in sugar cookie dough for 28 days. However it did note lab changes indicating a possible effect on liver enzymes, lowered triglycerides (which people take fenofibrates to achieve) and lab results related to kidney function.
Horses and cattle will eat these 2 ragweeds, most particularly when the plants are young, but even older plants of the milder, giant ragweed will be eaten by the cattle, These grazing animals don’t seem to like the lance leafed Ambrosia bidentata of the Mississippi valley, however sheep will tolerate that more resinous species, apparently. Greg Judy, (Regenerative Rancher) reports that his cattle go after the young giant ragweed even before they’ll eat clover, and I’d agree with his bovines on that matter :-D The ginger flavor is pretty nice.
The fastest way of self help for pollen allergies is directly eating the leaves, but some people like ethanolic tinctures. This, of course amounts to a significant dose reduction. Those with severe ragweed allergies or with homeopathic tendencies (wanting tiny doses) might prefer a slow introduction of ragweed to their lives for the goal of desensitization. Matthew Wood recommends just a bite of a the leaf, to be introduced during a hayfever sneezing episode, or a few drops of the 1:2 ethanolic tincture of fresh plant, and evaluating the reaction before scaling up the dose. Herbalists recommend that people with more significant allergies use a skin test with the young leaves, applied topically on the inner elbow, to check for a reaction before trying any internal usage.
The astringent qualities of Ambrosia can be noticed by the drying effect that is produced when chewing the leaves. The ‘hairy tongue’ feeling is milder than that from eating an underripe American persimmon. This astringency contributes to its abilities to stop bleeding of wounds. The astringent plus the anti-inflammatory effects allow ragweed leaves, or an infusion from them to be used topically for hemorrhoidal relief, and to soothe bug bites and stings. The tea has also been used to relieve sore throats and respiratory ailments such as pneumonia. It serves also as an anti-diarrheal and to treat fever. The wide ranging anti-microbial properties of Ambrosia allowed for its usage as a poultice for purulent wounds.
The sesquiterpenoid compounds of Ambrosia have been of particular interest to our pharmacognosy friends who have more recently been subjected to the onslought of ragweed pollen. An extensive array of these active compounds has been elucidated within A. artemisiifolia and other ragweeds. For just one example, ambrosin, a pseudoguainolide sesquiterpene lactone, with recognized anti-cancer activity, has also been found to inhibit NF-κβ. It has greater bioavailability than curcumin, and therefore more neuroprotective potential within the CNS by addressing the inflammation processes that can lead to plaque formaton and Alzheimers dementia. It performed well in a mouse model of lipopolysaccharide induced memory impairment, showing biochemical, histological and behavioral evidence of neuronal protection, opening different avenues to address Alzheimer’s disease and providing a molecular model for new potential preventions or treatments.
Very possibly, the rest of the world will come to appreciate the plus side of Ambrosia, the famously irritating gift from the Americas.
Do you have any personal encounters and adventures with ragweed that you’d like to share?
Where We Dig
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7. Ambrosia artemisiifolia (American Wormwood, Bitterweed, Blackweed, Carrot Weed, Common Ragweed, Hay Fever Weed, Ragweed) | North Carolina Extension Gardener Plant Toolbox. Accessed September 4, 2025. https://plants.ces.ncsu.edu/plants/ambrosia-artemisiifolia/
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9. Let’s Eat Common Ragweed and Make a Tincture! 🌿 (Ambrosia Artemisiifolia).; 2024. Accessed September 8, 2025. www.youtube.com/watch?v=08-MqabHCEo
10. Su P, Liu X, Wang R, et al. Autotoxicity of Ambrosia artemisiifolia and Ambrosia trifida and its significance for the regulation of intraspecific populations density. Sci Rep. 2022;12(1):17424. doi:10.1038/s41598-022-21344-8
11. Schaffner U, Steinbach S, Sun Y, et al. Biological weed control to relieve millions from Ambrosia allergies in Europe. Nat Commun. 2020;11(1):1745. doi:10.1038/s41467-020-15586-1
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Wonderful information, thank you!