by Erin Holden
While doing research for a presentation on herbal uses of native plants, I decided to look more into a plant I’d learned about in herb school, sweet flag (Acorus calamus). This strongly aromatic aquatic plant has long been my favorite warming digestive bitter for those times when I overindulge in a huge meal (I’m looking at you, Thanksgiving). The flavor is warm, pungent, bitter, and spicy in a black-peppery way – the flavor sort of fills up your mouth and is warm all the way down to your stomach. But as I dug deeper into the research, I discovered I’d been wrong all this time about the origin of the Acorus species I’d been using. It turns out that A. calamus is native to Europe, temperate India, and the Himalayan region, while the native species is A. americanus (also called sweet flag), although the two species look so similar that even some scientists are unsure of which species they’ve studied and reported on. There still isn’t much consensus among taxonomists as to what differentiates these two – some even classify them as the same species (Boufford,1993; eFloras, 2008). Let’s take a deeper look at the similarities and differences between these two plants.
There are many common names for sweet flag from all over the world (Daglan, 2014), many of which describe either the flavor of the root (like bitter, sweet, pepper) or its watery habitat:
Abenaki: mokwaswaskw (muskrat plant)
Ayurvedic Tradition: vacha
Cheyenne: wi’ukh is e’evo (bitter medicine)
Chinese Medicine: shui chang pú (watery flourishing weed)
English: sweet flag, calamus
Hudson Bay Cree: pow-e-men-arctic (fire or bitter pepper root)
Penobscot and Nanticoke: muskrat root
Micmac: ig gig’wesukwul (muskrat root)
Pawnee: kahtsha itu (medicine lying in water)
Many Native American names connect Acorus with muskrats. According to Sue Thompson’s dissertation on Acorus (as reported by Daglin, 2014):
There seems to be “a closely linked ecological relationship between Native Americans trapping muskrats and using Acorus, muskrats eating Acorus, and Acorus. Muskrat feeding habits may in part be responsible for the dispersal of Acorus, and Native Americans may have intentionally planted Acorus both for their own medicinal use and to ensure food for the muskrat, which was economically valuable to them (Morgan 1980). Thus, the many Native American names for Acorus, which involve muskrat as a root word, may reflect an important economic and ecological relationship among man, plants, and other wildlife.”
Both species are perennial, grow in zones 4 to 10, have 1’–3’ tall iris-like leaves, and can spread 1’–2’. They bloom April through June, and like full sun to part shade. The inflorescence is a green spadix with no spathe (a spathe is a hood-like structure, like the white part of a peace lily). Both A. americanus and A. calamus are freshwater aquatic plants that grow in medium to wet soil and can grow in up to nine inches of water. They’re both easily propagated by root/rhizome divisions in the spring. Since they are aquatic plants, they can be used in water gardens, ponds, or rain gardens. They can also grow in regular garden beds as long as they get adequate water, so they’re very versatile if you’re looking for tall, straight leaves (Missouri Botanical Garden, 2022).
Although the two species look very much alike, there are some subtle differences you can use to tell them apart. A. calamus has leaves with one prominent vein and undulate (wavy) margins, does not produce fruit, and will “appear to have a shriveled ovary” in late summer, whereas A. americanus has leaves with two to six veins and smooth margins, produces small green berries, and has swelling ovaries in late summer (Dalgin, 2014).
There are also some unseen differences between the two. It turns out that A. americanus is a fertile diploid species and contains almost no phenylpropanoids, a chemical family whose members play a role in the flavors and aromas of cinnamon, cloves, nutmeg, and sassafras. A. calamus is a (mostly) sterile triploid (there are some populations of a fertile diploid phenotype in Asia that are morphologically distinct from the North American A. americanus). In addition, 13% of its volatile oil fraction is made up of those phenylpropanoids, one of which is β-asarone.
This chemical distinction is important, because β-asarone has demonstrated procarcinogenic tendencies (meaning it could metabolize into a cancer causing compound), and the FDA has banned the use of “calamus, calamus oil, or extract of oil in food,” although these studies used high levels of isolated β-asarone and not “suggested doses of the whole plant in terms of mg/kg of body weight” that an herbalist would recommend. However, since A. americanus has little to no β-asarone, it’s been suggested that this species is safe to consume (Dalgin, 2014).
Sweet flag is an important plant for many native peoples. One writer said it is “considered so sacred [to the Cheyenne] that only qualified Sundance priests [can] collect it,” and it “may be the most important herb in Penobscot pharmacology” (Dalgin, 2014).
Historically, the Dakota used a paste on their faces to “instill fearlessness and provide stamina” in battle and chewed the rhizomes to enhance endurance “during the wars of the 20th century” (Dalgin, 2014).
Other uses for the plant include: colds, flu, and sore throat; as a tonic; for intestinal pain and as a carminative (dispels gas); as a stimulant when tired; toothache; an analgesic for muscle cramps/spasm; and in ceremonial/religious rituals.
Colonists also used Acorus, and Eclectic physicians (doctors in the 1800s) incorporated it into their materia medica (list of medicinal substances). Eventually, it made its way into the first edition of the Dispensatory of the United States in 1833 (Osol et al, 1833), which cataloged drugs used by U.S. pharmacists at the time. These groups used it pretty much the same way that Native Americans use it: as a carminative, for weak digestion and flatulent colic, as a sialagogue (stimulates saliva production) and as “breath perfume,” a warming aromatic bitter, and externally for ulcers that wouldn’t heal (Dalgin, 2014).
Some modern herbalists who use both species say that, because of its higher volatile oil content, A. calamus targets the gastrointestinal system more specifically, while A. americanus has a “more balanced” action on the whole body—working equally on the gastrointestinal and nervous system, as an expectorant (which helps clear gunk from the lungs), spasmolytic (calms spasms), and antitussive (Daglin, 2014).
Now that I know about A. americanus and its different effects on the body, I’m interested in experimenting with the two species. I’ve also planted it out in the Native American bed in the National Herb Garden. I wonder if we should also invest in a muskrat.
Photo Credits: 1) Acorus calamus inflorescence (E. Holden); 2) Muskrat (Linda Tanner, via Wikimedia ); 3) Acorus sp. used as a mass border planting (KENPEI, via Wikimedia ); 4) Two prominent veins and smooth leaf margins of A. americanus (E. Holden); 5) The prominent midvein and undulate leaf margins of A. calamus (E. Holden); 6) Botanical illustration of A. calamus (Creative Commons, Rawpixal LTD); 7) Acorus americanus growing along a stream bank (Ryan Hodnett, via Wikimedia)
Medicinal Disclaimer: It is the policy of The Herb Society of America, Inc. not to advise or recommend herbs for medicinal or health use. This information is intended for educational purposes only and should not be considered as a recommendation or an endorsement of any particular medical or health treatment. Please consult a health care provider before pursuing any herbal treatments.
References
Boufford, D. E. 1993+. Acorus. In: Flora of North America Editorial Committee, eds. Flora of North America North of Mexico [Online]. 22+ vols. New York and Oxford. Vol. 3. Accessed 10/5/22. Available from http://beta.floranorthamerica.org/Acorus
Dalgin, R. 2014. Acorus calamus and Acorus americanus. Integrative Herbalism: Journal of the Vermont Center for Integrative Herbalism. Summer, 30-78.
eFloras. (Internet). 2008. Acorus calamus. Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA. Accessed 10/5/2022. Available from http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=200027130
Lady Bird Johnson Wildflower Center. (Internet). 2015. Acorus americanus (Raf.) Raf. Accessed 1/7/2022. Available from https://www.wildflower.org/plants/result.php?id_plant=ACAM
Missouri Botanical Garden. 2022. Acorus calamus. Accessed 1/7/2022. Available from https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=276172
Orsol, A., C. H. LaWall, F. Bache, G. B. Wood, G. E. Farrar, H. C. Wood Jr., and J. P. Remington. The dispensatory of the United States of America. Grigg & Elliot: Wisconsin. Available from https://www.google.com/books/edition/The_Dispensatory_of_the_United_States_of/xikzAQAAMAAJ?hl=en&gbpv=1
Erin is the gardener for the National Herb Garden at the U.S. National Arboretum in Washington, D.C. She is a member of the American Herbalists Guild, United Plant Savers, and a member-at-large of the Herb Society of America.
Many people may be familiar with the distinctive aroma of valerian root; old socks, wet dog, and horse manure are just a few things to which the odor has been affectionately compared. In fact, the constituent responsible for the smell, valeric acid, is also one of the components that causes swine manure to smell so badly (Chi, Lin, & Leu, 2005). Despite its odiferous qualities, valerian has been used for its sedative effects for over 2000 years. Valerian root is taken to relieve anxiety, promote sleep, and relax gastrointestinal spasms (Braun & Cohen, 2006). Some research shows that another compound, valerenic acid, may mediate anxiety by binding to GABA receptors in the brain, although the exact medicinally active compounds haven’t yet been pinpointed (Benke et al., 2009). It’s possible that valeric acid also has a role to play, as multiple constituents acting together may account for these effects (Spinella, 2002).
Glycosaminoglycans, the medicinally active polysaccharides found in marshmallow root, have an appropriate abbreviation: GAGs. Mixing the powdered root with water or preparing an infused tea results in a slimy, mucilaginous mess that can be difficult to choke down. But it’s this very sliminess that causes marshmallow to work so well at soothing irritated tissue. Marshmallow is used for coughs, as a urinary demulcent, and for irritated skin. The mucilage forms a bioadhesive layer that acts as a barrier, protecting the tissue and allowing it to heal (Deters et al., 2010). Extracts of the root have also demonstrated antibacterial properties (Lauk, Lo Bue, Milazzo, Rapisarda, & Blandino, 2003; 
No pub or bar would be complete without a bottle of bitters, with Angostura® being among the more popular brands. Although the recipe for Angostura® Bitters is a well-guarded secret, gentian is listed on the label as an ingredient and is likely a major contributor to the bitter flavor. By itself, gentian is considered extremely bitter and has been used as a yardstick when rating the bitterness of other herbs (Olivier & van Wyk, 2013). Bitter compounds in general have been shown to stimulate the secretion of saliva and digestive juices by activating the vagus nerve (Bone, 2003). The active constituents in gentian, gentiopicroside and amarogentin, are no exception. These molecules account for gentian’s use in improving digestion, increasing appetite, and relieving flatulence (Braun & Cohen, 2006).
What list of nasty herbs would be complete without pukeweed? This alternate common name for lobelia says it all. The emetic qualities of this plant were made (in)famous by Dr. Samuel Thomson in the 19
I was visiting my mother just a few weeks before Christmas in 2017. She had recently moved to a wonderful small family-run assisted living home. The owner, Ann Abdul, asked me if I’d like to taste some “sorrel drink” she had made for the holiday season. I had no idea what that was. It looked Christmassy–a brilliant ruby red. I took a sip, and the most delicious taste filled my mouth. It was a rich, complex, and unfamiliar burst of flavors. But it tasted like Christmas, too—it was sweet, and I thought I could detect cinnamon, cloves, and vanilla. But it also tasted a bit like lemonade with a pronounced citrusy tartness. I loved it, and I had to know more! 
It turned out that “sorrel” is a name for the calyces of Hibiscus sabdariffa, a plant commonly known as roselle, as well as the beverage that is made from them. If you have ever tasted Celestial Seasonings Red Zinger tea, then you have tasted sorrel. (This sorrel is not related to the leaves of 
Another essential Trinidadian Christmas drink is one more familiar to most Americans. Ponche de crème is their flavorful take on eggnog. Served straight or spiked with rum, this delicious drink must contain a special Trinidad ingredient: Angostura Bitters. You may be familiar with 
Lastly, the third beverage essential to Christmas in Trinidad is also enjoyed year-round: ginger beer. Ginger beer is a strongly flavored version of ginger ale that is non-alcoholic. The rhizome of Zingiber officinalis contains volatile oils, such as zingerone and gingerols, that give ginger its characteristic “zing.” Most families in Trinidad, as well as the rest of the Caribbean, make their ginger beer at home from fresh ginger rhizomes, and the resulting ginger beer often has a very strong punch of ginger flavor. It contains other spices such as cinnamon and clove. It is made very strong, and it can be diluted with water or club soda to suit your taste.
1 package dried sorrel (Angel brand easily available online or in Caribbean market)
herbal, bittersweet liqueur as an aperitif or digestif”, to either stimulate or aid digestion before or after a meal (Parsons, 2011). However, during the 1850s in the United States, the temperance movement, along with high taxes on potable alcohol (alcohol consumed as a beverage), forced these types of drinks to fall out of favor, and led to the increased popularity of stomach bitters, a nonpotable alcohol (so not subject to the same taxes). Unfortunately, many unscrupulous companies began making outlandish claims for their products, forcing the federal government to step in and lay down restrictions. This, along with Prohibition in 1919, knocked bitters off the U.S. map for a good long while.
In Food: Many countries that traditionally partake of alcoholic bitters also have a history of harvesting and consuming bitter spring greens. Plants such as burdock, dandelion, and cresses pop up early in the spring, and their bitter leaves not only helped stimulate digestive systems turned sluggish from a winter of consuming preserved foods, but provided much needed vitamins and minerals. Additionally, many bitter plants are anthelmintic, meaning they help kill intestinal worms. It gives new meaning to the term “spring cleaning!”
common name comes from its use in killing intestinal parasites. Cinchona (Cinchona spp.) is the botanical source of quinine, the widely used antimalarial agent. Gentian (Gentiana lutea), the archetypal bitter, is a main ingredient in most commercially available cocktail bitters, including Angostura Bitters. Some plants that don’t have an overt bitter flavor, such as fennel (Foeniculum vulgare) and ginger (Zingiber officinale), are also sometimes classified as “bitters” by herbalists due to their therapeutic action on the digestive system.
The main reason plants create bitter compounds boils down to one simple thing: defense. Since plants can’t run and hide from predators, they devised their own chemical defense system – the first instance of chemical warfare, you could say. When an insect bites into, say, a broccoli plant, it gets a mouthful of glucosinolates, sulfur containing compounds that are toxic to insects and rodents, and gross to some people. Plants see us as essentially giant rodents that want to eat them, and create a wide variety of nasty tasting compounds to deter us from doing so. In turn, since some of these compounds not only taste bad but can also kill humans, we evolved taste receptors to detect them, therefore potentially skirting death.
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