Yarrow

Yarrow is quite common, growing along roads and open fields. Notable for its lacy leaf structure.

Common Name: Yarrow, Woundwort, Milfoil, Staunch weed, Thousand-leaf, Old Man’s Pepper, Bloodwort, Devil’s nettle – Yarrow is the English variant of the Anglo-Saxon word gearwe originally from Old High German garwa. There are many colloquial names in different languages and localities. The German schafgarbe, French herbe à dinde, Swedish rölleka, and Italian achillea are all yarrow by another name.

Scientific Name: Achillea millefolium – The name of Achilles, the Greek hero of Homer’s Iliad, is recognizable as the genus. The species name means “thousand-leaf” in Latin ―  one of the common names. The distinctive appearance is characterized by small fern-like leaves extending outward from the upright stem holding up a white bouquet.

Potpourri: Yarrow is one of the most common and well-known medicinal herbs in the world. With a circumboreal reach, it encompasses the temperate regions of the northern hemisphere spanning both Eurasia and North America across a broad swath of latitudes. It grows in open areas in copious clusters marking its location with flat topped clusters of white flowers, one of three species in the mid-Atlantic region with similar appearance. The other two are white snakeroot, the poisonous weed that killed Abraham Lincoln’s mother and Queen Anne’s lace, the wild carrot, both of which are in the Aster family. Yarrow is a composite flower of the Daisy family, the flower-like “head” consisting of many small flowers. Familiarity and ease of identification favored experimentation by native peoples globally, using it in the treatment of a variety of medical conditions that vary according to tribe and custom.[1] Both Native Americans and the Europeans who ventured westward across the Atlantic independently exploited yarrow’s unusual chemistry according to their widely divergent traditions. Yarrow is one of the few (and possibly the only) plants with that distinction. Other herbals used in the colonial era were either imported from Europe like heal-all or adapted from local Indian usage like black cohosh.

The ancestry of yarrow extends to the origins of Western civilization. Achillea is an eponym for Achilles, the main Greek protagonist in Homer’s Iliad that chronicles the Trojan War. He was killed with an arrow that struck him in the heel left unprotected when he was dipped into the magical river Styx ― Achilles’ heel a consequent metaphor for anything vulnerable. Greek mythology attributes the education of Achilles to the centaur Chiron, an expert in herbal medicine where he learned of the healing powers of yarrow.  Used to staunch the wounds of fallen Greek warriors at Troy, yarrow thereafter became known as herba militaris, Latin for military medicine and retained in the common name woundwort. While the Homeric tale is certainly apocryphal, knowledge of the healing properties of yarrow was well established from the earliest days throughout Europe. This is evident from its continued use as traditional medicine in many countries. [2] Achillea was the obvious choice for the genus when Linnaean taxonomy was first established in the eighteenth century.

Yarrow is a composite flower – the “head” is composed of many small flowers

The extent to which yarrow is accepted in Europe as an effective medicinal herb is evidenced by the publication of an assessment report by the European Medicines Agency in 2020. Citing the “whole or cut, dried flowering tops” as the most effective part of the plant, the prescription  is for a minimum of 2 milliliters per kilogram of “essential oils.”  Based in part on the inclusion of  Achillea millefolium in the Pharmacopoeias (approved drug lists) of Great Britain, France, Hungary, Austria, Romania, and the Czech Republic and also in the German Commission E Monograph, the assessment report lists its accepted medical uses in the various jurisdictions. Not surprisingly, the original Achillean wound use is the most prevalent. Topical application of the essential oil staunches bleeding from the nose or anywhere else, improves wound healing, and reduces skin inflammation. Taken internally, the most common treatment is for gastrointestinal difficulties such as loss of appetite and upset stomach. However, it is also used to treat colds in Great Britain, “cramp-like conditions of psychosomatic origin” in Germany, and spasmodic colitis in France. [3] It is likely that Europeans also had many other local customary uses with their own local historical traditions which gradually coalesced into those few found more effective and reliable across the continent as cities and commerce expanded. One example is its use as snuff from which the name Old Man’s Pepper derives.

On the other side of the North Atlantic, Native Americans employed yarrow more extensively. Applications ranged from specific symptoms to panacea. Cherokee of the Southeast used yarrow mostly for hemorrhages both internally and externally, taking advantage of its astringency. They also smoked the leaves to treat catarrh, a condition resulting from excessive mucous production. Further west the Blackfoot Indians of the Great Lakes region used it as a cure-all, rubbing whatever body part was affected by sickness.  In one of the few documented veterinary applications, they also made an eyewash for their horses. On the Great Plains, the Cheyenne used an infusion of dried leaves and flowers to treat just about anything, including chest pains, nausea, cold, coughs, fevers, and respiratory diseases. [4] There are many other references to the use of yarrow by Native Americans. According to the USDA database “Native Americans used tea made from common yarrow to relieve ear-, tooth-, and headaches; as an eyewash; to reduce swelling; and as a tonic or stimulant.” [5] Since there was minimal intertribal coordination and communication with a fair amount of rivalry and some conflict, there were few opportunities for tribal healers to learn of and employ common remedies for similar ailments.

There is a good reason for the diverse and sometimes contradictory uses of yarrow. It has a complex chemistry with more than 100 biologically active chemicals. [6] According to the European yarrow report, it contains “3-4% condensed and hydrolysable tannins; 0.3-1.4% volatile oils, mostly linalool, borneol, camphor, β-caryophyllene, 1,8-cineole, and sesquiterpene lactones composed of guaianolides, mainly achillicin … and flavonoids (apigenin, luteolin, isorhamnetin, rutin).” This is in addition to an impressive array of amino acids,  fatty acids, vitamins,  alkaloids, bases,  alkanes, saponins,  sterols, sugars, and at least one poison (thujone). Knowing yarrow chemistry is one thing. Knowing what the chemical compounds do is quite another. Limited research attributes the salubrious effects of yarrow to the essential, volatile oils and sesquiterpene lactones. However, every one of the constituents is naturally produced by yarrow for some reason and that must in some cases be to deter browsing animals and sucking insects. The ASPCA lists yarrow as toxic to dogs, cats, and horses, causing vomiting, diarrhea, and dermatitis. [7]  Some birds use yarrow to build their nests, which has been shown to reduce the number of fleas by fifty percent. [8] Conversely, the USDA estimates that 20 percent of cattle and horses and 40 percent of sheep and goats graze on yarrow with no ill effects and evident nutrition.

The contradictory effects of advertent yarrow consumption by humans and domesticated animals can be attributed to chemical differences according to geography, habitat, and hybridization. Many plants form hybrids due to variations in the numbers of chromosomes. Most living things are diploid, having two sets of chromosomes excepting the sex cells that are haploid (23 chromosomes in humans) that join to form the diploid gamete. Having more than two sets is called polyploidy.  Yarrow is in something of a class by itself, with diploid, tetraploid, pentaploid, hexaploid, septaploid, and octoploid variants.[9] Since there is no commercial motivation to fund a detailed study of yarrow’s variability according to genetics (it is a weed after all) there is little scientific data. One of the few studies consisted of testing up to forty yarrow plants from each of sixty six sites to correlate polyploidy with chemistry. Hexaploid yarrows found in dry and nutrient-poor habitats had low levels of achillicin, one of the sesquiterpene lactones. Tetraploid yarrows had high levels of achillicin that correlated to the presence of phosphate, magnesium, and manganese in the soil. Noting that “the concentration varies widely in a population of a species,” the study concluded that “This makes the use of herbal medicine difficult.” [10] It is reasonable to conclude that the diverse and contradictory effects of consuming yarrow as either food or medicine is due to local variations in the quantity and quality of the many chemical compounds.

The fact that yarrow from one field may be different from yarrow in another field has not stopped the herbalists from extolling its virtues indiscriminately. In one herbal characterized as a Gaia original (The Greek personification of Earth), yarrow is noted for its “actions” that include “diaphoretic, febrifuge, peripheral vasodilator, hypotensive, antithrombotic, vulnerary, styptic, emmenagogue, anti-inflammatory, astringent, diuretic, digestive, and antiseptic.” That seems to cover about everything except cancer and athlete’s foot. A “hot infusion” of yarrow lowers fever by causing sweating to eliminate toxins and lowers blood pressure while simultaneously getting rid of  blood clots. Good for the stomach to improve digestion while getting rid of ulcers, yarrow also works on arthritis and rheumatism. In the “stops bleeding” category, reducing excessive menstruation and treating bleeding piles are included. [11] And this is one of the more rational prescriptions, based at least in part on traditional use of some type of yarrow somewhere. For those who adhere to the 17th century Doctrine of Signatures as a basis for establishing medicinal purpose, one gets “the umbel-like umbrella of yarrow betrays its properties to reinforce the protective auric shield.” What this golden (Au is the symbol for the element gold, aurum in Latin) shield is supposed to do is not clear, but a further explanation provides “lacy leaves and umbel flowers represent aeration of the lungs and blood stream.” [12] I wonder why?

Those who favor herbal remedies over pills and potions dispensed by the pharmaceutical industry believe they are on moral high ground. It is certainly true that the only drugs were herbs up until the dawn of the 20th century. There was no aspirin for headache and no erythromycin for strep throat. The apothecary shop contained dried herbs and tinctures of various mixtures … but there were also ingredients like bat wings and tiger pee. Some of the traditional herbal remedies actually worked and have since taken their place on the drug store shelf. Some natural substances like opium, have been synthesized; heroin was originally marketed as a pain reliever until addiction emerged as a serious problem. The subsequent opioid epidemic has forever tainted the reputation of big pharma.  However, absent a scientific trial with an untreated control group to use as a baseline for measuring different outcomes, there can be no confirmation of the benefits of any herbal product beyond anecdote. Trials are expensive and drug companies are only willing (and able) to foot the bill if subsequent profits on sales can pay for the research and development. The placebo effect and different reactions to the same drug by different individuals all add to the confusion. The bottom line is that herbal supplements taken for general health and well being are generally benign, and, if you believe they work, they probably do. However, most people who are really sick go see a doctor who prescribes medications from the pharmacy and not the woods. This would include yarrow, in spite of its historical herbal heritage.

References

1. Niering, W. and Olmstead, N National Audubon Society Field Guide to North American Wildflowers, Alfred A Knopf, New York, 1998, pp 354-355.

2. https://www.botanical.com/botanical/mgmh/y/yarrow02.html      

3. Assessment report on Achillea millefolium L., herba European Medicines Agency, 23 September 2020. https://www.ema.europa.eu/en/documents/herbal-report/final-assessment-report-achillea-millefolium-l-herba-revision-1_en.pdf    

4.  Ethnobotany database for Native American plant medicinal usage. http://naeb.brit.org/uses/search/?string=Achillea+millefolium+   

5. https://www.fs.fed.us/database/feis/plants/forb/achmil/all.html  

6. Foster, S. and Duke, J. Eastern Central Medicinal Plants and Herbs, Houghton Mifflin, Boston, 2000, p 74.        

7.  https://www.aspca.org/pet-care/animal-poison-control/toxic-and-non-toxic-plants/yarrow    

8. Shutler D, Campbell A. “Experimental addition of greenery reduces flea loads in nests of a non-greenery using species, the tree swallow Tachycineta bicolor“. Journal of Avian Biology. 8 September 2007 Volume 38 Number 1 pp 7–12.  

9. http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=200023010   

10. Michler, B.  and Arnold, C. . “Predicting Presence of Proazulenes in the Achillea millefolium Group”. Folia Geobotanica. 1999  Volume 34 Number 1 pp 143–161.

11. McIntyre, A. Herbs for Common Ailments, Simon and Shuster, New York, 1992, p 60.

12. Graves, J. The Language of Plants, Lindisfarne Books, Great Barrington, Massachusetts, 2012, p 122.

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